[gimp-web-devel/pat/bootstrap] content: more fixes and adding back Hacking:Problems_and_solutions.

From: Jehan <jehanp src gnome org>
To: commits-list gnome org
Cc:
Subject: [gimp-web-devel/pat/bootstrap] content: more fixes and adding back Hacking:Problems_and_solutions.
Date: Tue, 6 Sep 2022 22:04:32 +0000 (UTC)
commit dcc7e59822443af5916a254390a96fd90d997795
Author: Jehan <jehan girinstud io>
Date:   Wed Sep 7 00:03:25 2022 +0200

    content: more fixes and adding back Hacking:Problems_and_solutions.

 content/core/setup/build/Linux.md                  |   21 +-
 content/core/setup/build/Problems_and_solutions.md | 1099 ++++++++++++++++++++
 content/core/setup/build/Windows.md                |   28 +-
 content/core/setup/build/_index.md                 |    2 +-
 content/core/setup/build/macOS.md                  |    2 +-
 5 files changed, 1119 insertions(+), 33 deletions(-)
---
diff --git a/content/core/setup/build/Linux.md b/content/core/setup/build/Linux.md
index 46d0bc4..723f8a3 100644
--- a/content/core/setup/build/Linux.md
+++ b/content/core/setup/build/Linux.md
@@ -14,8 +14,8 @@ This page is for Linux-specific additions to that page.
 
 GIMP depends on many packages in addition to <code>babl</code>, <code>gegl</code>, <code>libmypaint</code> 
and <code>mypaint-brushes</code>.
 
-Gimp.org may change the requirements for each Gimp release.
-Gimp.org changes which packages are required.
+gimp.org may change the requirements for each GIMP release.
+gimp.org changes which packages are required.
 The package names generally do not change.
 Build options affect which packages are required.
 
@@ -26,7 +26,8 @@ This page lists dependencies for some linux distributions, on certain dates, wit
 
 Working in October 2019.
 
-<pre>sudo apt install \
+```sh
+sudo apt install \
     libtool intltool \
     meson \
     asciidoc \
@@ -67,16 +68,10 @@ Working in October 2019.
     ruby \
     w3m \
     xsltproc
-</pre>
+```
 
-Added in 2020, when building optional vala language plugins, the vala compiler tool:
+Added in 2020, when building optional vala language plugins, the vala compiler tool: `valac`
 
-<pre>    valac
-</pre>
+Since Ubuntu 20.04 focal, the tool `gtk-encode-symbolic-svg`, an executable binary, has moved from package 
`gtk-3-examples` to package `libgtk-3-bin`.
 
-Since Ubuntu 20.04 focal, the tool gtk-encode-symbolic-svg, an executable binary, has moved from package 
gtk-3-examples to package libgtk-3-bin.
-
-Since 2021, when building using the clang compiler, the OpenMP library i.e. -lomp :
-
-<pre>    libomp-dev
-</pre>
+Since 2021, when building using the clang compiler, the OpenMP library i.e. `-lomp`: `libomp-dev`
diff --git a/content/core/setup/build/Problems_and_solutions.md 
b/content/core/setup/build/Problems_and_solutions.md
new file mode 100644
index 0000000..286149d
--- /dev/null
+++ b/content/core/setup/build/Problems_and_solutions.md
@@ -0,0 +1,1099 @@
+---
+title: "Building: problems and solutions"
+Author: "GIMP team"
+Date: 2021-08-18
+weight: 5
+---
+
+This page describes problems/solutions that hamper GIMP developers. It's a knowledge base for developers.
+Feel free to add your own findings and don't be shy. It makes the work easier for all of us.
+
+
+## Build
+
+### General
+
+#### Libraries versions too low
+
+I’m getting an error about a too low of GTK+/GLib while compiling XXX
+
+You can either update your version of GTK+/GLib using your system’s package manager, or compile GTK+/GLib 
from source! Compiling these is done exactly like we compiled babl – download the source (either the latest 
from Git, or a package from the official site), compile and install. You may also need to do something like 
this to a library called ATK.
+
+
+
+
+
+#### Error while loading shared libraries: No such file or directory
+
+'''Problem: I've built a shared library. However, building fails with the message 'error while loading 
shared libraries: libmylibrary.so.1: cannot open shared object file: No such file or directory' '''
+'''Cause:'''
+The linker doesn't find your library, because it's not in a standard location (such as /usr/lib).
+
+'''Solution:'''
+Set the environment variable LD_LIBRARY_PATH to the directory which contains your compiled library.
+
+Example: given the library is in /home/username/build/mylibrary/lib then type '''export 
LD_LIBRARY_PATH=/home/username/build/mylibrary/lib:${LD_LIBRARY_PATH}''' and try again.
+
+
+
+
+
+#### No rule to make target 'all'
+
+'''Problem: I've created a new subdirectory and the Makefile.am file there. However, each time the ''make'' 
command stops at this directory with the error 'No rule to make target all''''
+'''Cause:'''
+The directory isn't listed among AC_CONFIG_FILES in the '''configure.ac''' file. Therefore the generated 
makefile doesn't contain the target 'all' and the ''make'' command doesn't know what to do.
+
+'''Solution:'''
+
+* Open `configure.ac` in the project's root directory.
+* Search for the line `AC_CONFIG_FILES`.
+* In the following list look for a suitable line to place your new directory item. The line after the parent 
directory, taking care for the alphabetical order, is a good candidate.
+* Save `configure.ac`.
+* Open a terminal window and change to the directory where you build the project.
+* Run `autogen.sh --prefix=$your_prefix`
+
+
+
+#### Make install fails with 'cannot install to a directory'...
+
+'''Problem: make install fails with ''error:cannot install ... to a directory not ending in ...'' '''
+
+You get error messages like this
+
+```sh
+make[3]: Entering directory `/home/$your_username/build/gegl-master/operations/core'
+/usr/bin/install -c -d /home/$your_username/gimp-install/gimp-feature2/lib/gegl-0.3
+for i in clone.la convert-format.la crop.la nop.la; do \
+         /bin/bash ../../libtool --mode=install /usr/bin/install -c $i 
/home/$your_username/gimp-install/gimp-feature2/lib/gegl-0.3 ; \
+       done
+libtool: install: error: cannot install `clone.la' to a directory not ending in 
/home/$your_username/gimp-install/gimp-master/lib/gegl-0.3
+libtool: install: error: cannot install `convert-format.la' to a directory not ending in 
/home/$your_username/gimp-install/gimp-master/lib/gegl-0.3
+libtool: install: error: cannot install `crop.la' to a directory not ending in 
/home/$your_username/gimp-install/gimp-master/lib/gegl-0.3
+libtool: install: error: cannot install `nop.la' to a directory not ending in 
/home/$your_username/gimp-install/gimp-master/lib/gegl-0.3
+make[3]: *** [install-exec-local] Error 1
+make[3]: Leaving directory `/home/$your_username/build/gegl-master/operations/core'
+make[2]: *** [install-am] Error 2
+make[2]: Leaving directory `/home/$your_username/build/gegl-master/operations/core'
+make[1]: *** [install-recursive] Error 1
+make[1]: Leaving directory `/home/$your_username/build/gegl-master/operations'
+make: *** [install-recursive] Error 1
+```
+
+'''Cause:'''
+In a former step you've built into another prefix. Somehow the newer build reads remains of that in the 
aforementioned *.la files and stumbles over them.
+
+'''Solution:'''
+
+The solution describes the process using the example of GEGL.
+
+
+* Change into the build directory of that previous build (in the given example this is  
`/home/$your_username/build/gegl-master/operations/core`, or into its root folder, here: 
`/home/$your_username/build/gegl-master`)
+* Run `make clean`.
+* Set your `INSTALL_PREFIX` variable properly to the folder where you want GEGL install in.
+* Change into the folder where you build GEGL from (if you're not already there).
+* Re-run `configure --prefix=$INSTALL_PREFIX` (or if you checked GEGL out from Git: `autogen.sh 
--prefix=$INSTALL_PREFIX && make && make install`
+
+#### Absolute DESTDIR required
+
+If you have weird errors at installation, they may be due to DESTDIR being a relative path.
+
+
+### BABL
+
+#### Unit tests fail
+
+'''Problem: Unit tests pass on one machine, but fail on another - equally configured - machine.'''
+
+In this particular case the tests RGBA-&gt;HSLA and RGBA-&gt;HSVA passed on an amd64 platform, but failed on 
an i386 platform.
+
+This is the content of file tests/testsuite.log on the i386 machine:
+
+```sh
+#### ===============================
+babl 0.1.11: tests/test-suite.log
+#### ===============================
+# TOTAL: 19
+# PASS:  17
+# SKIP:  0
+# XFAIL: 0
+# FAIL:  2
+# XPASS: 0
+# ERROR: 0
+
+.. contents:: :depth: 2
+FAIL: hsl
+#### =
+rgba to hsla  failed #0[0]  got 0.166667 expected 0.000000
+rgba to hsla  failed #1[0]  got 0.666667 expected 0.000000
+FAIL: hsva
+#### =
+rgba to hsva  failed #0[0]  got 0.166667 expected 0.000000
+rgba to hsva  failed #1[0]  got 0.166667 expected 0.000000
+```
+
+'''Cause:'''
+The tested code doesn't take into account that strict equality comparisons (==) will most often lead to 
different results on different platforms.
+
+'''Solution:'''
+The code must take this fact into account. This means:
+
+
+* '''Don't use == for floating point comparisons!'''
+
+The following lines show alternatives.
+
+1. Make sure to have defined EPSILON first:
+
+```C
+#define EPSILON 1.0e-10
+```
+
+2. Use EPSILON instead of == :
+
+
+| wrong | right |
+| ----- | ----- |
+| `if (value == 0.0)` |  `if (value < EPSILON)`
+| `if (value1 == value2)` |  `if (value1 - value2 < EPSILON)` or `if (fabs (value1 - value2)) < EPSILON` |
+
+See also [Bugfix for RGBA-&gt;HSLA,HSVA 
conversions](https://git.gnome.org/browse/babl/commit/?id=da3b41274052c23b44ad8eceb9d99106d2739f3a).
+
+
+* Make sure, your code works on all architectures. On a 64 bit machine this would mean also to compile and 
run `make check` with `CFLAGS="-O2 -mfpmath=387"`.
+
+If you're unsure, come to IRC (channels <a class="external text" href="irc://irc.gimp.org/gimp" 
rel="nofollow">#gimp</a> or <a class="external text" href="irc://irc.gimp.org/gegl" rel="nofollow">#gegl</a>) 
and ask.
+
+
+### GEGL
+
+#### GEGL build breaks for failing GLib assertions
+
+'''Problem: Building GEGL master stops with failing assertions related to GLib. The stopped build can't be 
aborted with Ctrl+C to enter new commands in that terminal session.'''
+
+The following messages are shown at the screen:
+
+```sh
+CC       gegl-matrix.lo
+CCLD     libgegl-0.3.la
+GISCAN Gegl-0.3.gir
+GLib-GObject-CRITICAL **: gtype.c:2720: You forgot to call g_type_init()
+GLib-GObject-CRITICAL **: g_type_interface_add_prerequisite: assertion `G_TYPE_IS_INTERFACE 
(interface_type)' failed
+GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
+GLib-GObject-CRITICAL **: gtype.c:2720: You forgot to call g_type_init()
+GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
+GLib-GObject-CRITICAL **: gtype.c:2720: You forgot to call g_type_init()
+GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
+```
+
+'''Cause:'''
+You have an old GLib version in your prefix. (Don't be fooled by just looking at the libglib version in your 
package manager!)
+
+'''Solution:'''
+
+* Close this terminal session and open a new one.
+* Remove that old GLib version from your prefix and rebuild GEGL from scratch.
+
+#### SPIRO not found
+
+'''Problem: I have SPIRO (packages libspiro0, libspiro-dev) installed. However, at the end GEGLs configure 
step tells me, that no usable SPIRO was found.'''
+
+GEGL builds and works anyway, because it is only an optional dependency.
+
+'''Cause:'''
+The package of your distribution doesn't contain the link libspiro.so to the actual SPIRO library. On a 
Debian testing system this concerns the package libspiro0.
+
+'''Solution:'''
+You have to set that link yourself.
+This bug is already known to the responsible 
[http://lists.alioth.debian.org/pipermail/pkg-fonts-devel/2013-September/012940.html Debian package managers].
+
+On an i386 platform:
+
+
+* '''cd /usr/lib/i386-linux-gnu'''
+* Find out the actual libspiro file: '''ls -l libspiro.*''' The actual libspiro file is a plain file, not a 
symbolic link, and has a name similar to libspiro.so.0.0.1
+* Set the link: '''sudo ln -s libspiro.so.0.0.1 libspiro.so'''. You will have to enter your password for 
this.
+* Point your LDFLAGS variable to that directory: '''export LDFLAGS="${LDFLAGS} -L/usr/lib/i386-linux-gnu"'''
+* Point your LD_LIBRARY_PATH variable to that directory: '''export 
LD_LIBRARY_PATH="/usr/lib/i386-linux-gnu:${LD_LIBRARY_PATH}"'''
+
+If you're working on an AMD64 platform, replace i386-linux-gnu by x86_64-linux-gnu.
+
+
+
+
+
+#### GEGL build breaks: 'recipe for target 'Gegl-0.3.gir' failed'
+
+'''Problem:'''
+
+The GEGL build breaks with a message like this:
+
+```sh
+Workspace/gegl/gegl/gegl-introspection-support.h:162:
+Warning: Gegl: GObject-Introspection specific GTK-Doc tag "Rename to" has been deprecated,
+please use annotations on the identifier instead:
+ * Rename to: gegl_buffer_set
+   ^
+/home/username/Build/gegl-master-linux/gegl/tmp-introspect4OKYKn/Gegl-0.3.o:
+(.data+0x4): undefined reference to `gegl_orientation_get_type'
+collect2: error: ld returned 1 exit status
+linking of temporary binary failed: Command '['/bin/bash', '../libtool',
+'--mode=link', '--tag=CC', '--silent', 'cc', '-o',
+'/home/username/Build/gegl-master-linux/gegl/tmp-introspect4OKYKn/Gegl-0.3',
+'-export-dynamic', '-I/home/username/Builds/gimp-master-linux/include',
+'-I/usr/include', '-g', '-O3', '-mmmx', '-msse', '-ftree-vectorize',
+'-ffast-math', '-Wall', '-Wdeclaration-after-statement', '-Wmissing-prototypes',
+'-Wmissing-declarations', '-Winit-self', '-Wpointer-arith', '-Wold-style-definition',
+'-DG_LOG_DOMAIN="GEGL-"__FILE__', '-L/usr/lib', '-L/usr/lib/i386-linux-gnu',
+'-L/home/username/Builds/gimp-master-linux/lib',
+'/home/username/Build/gegl-master-linux/gegl/tmp-introspect4OKYKn/Gegl-0.3.o',
+'-L.', 'libgegl-0.3.la', '-lgio-2.0', '-lgobject-2.0', '-Wl,--export-dynamic',
+'-lgmodule-2.0', '-pthread', '-lglib-2.0']'
+returned non-zero exit status 1
+/usr/share/gobject-introspection-1.0/Makefile.introspection:153: recipe for target 'Gegl-0.3.gir' failed
+make[3]: *** [Gegl-0.3.gir] Error 1
+```
+
+'''Cause:'''
+
+You triggered regeneration of autogenerated files, which overwrite new ones from the repository.
+
+'''Solution:'''
+
+* Clean your build directory:
+    + If you have built in the GEGL source directory, run '''git clean -xdf'''
+    + If you have built in another directory than your source directory: '''cd $build_directory &amp;&amp; 
rm -rf *'''
+* Build GEGL again.
+
+### GIMP
+
+#### GIMP build breaks for missing files in $ANOTHER_PREFIX/lib
+
+'''Problem: Building GIMP fails for instance in libgimpcolor with a message telling you, that some files in 
$ANOTHER_PREFIX/lib are missing and thus building libgimpcolor.la (or another *.la file) failed.'''
+'''Cause:'''
+You switched over to another prefix. You already cleaned or removed that old prefix, but in your new prefix 
are some files referring to other files in that old prefix.
+In other words - there's an evil mixture of your new prefix and some old prefix zombies and libtool trips 
you up ;-)
+
+'''Solution:'''
+Finding out the actually errorneous parts can take you hours, so it's better to make a clean sweep:
+
+
+* Check your environment variables, especially the build environment variables. If they point to that old 
prefix, change them to point to the new prefix.
+* Drop the contents of your new prefix.
+* Rebuild from scratch. For BABL, GEGL and GIMP (and other libraries, if you use them):
+    + Change to their directory.
+    + Save your work (backup your working files or do '''git stash''').
+    + Run '''git clean -xdf''' or drop the contents of the workspace except the .git folder or the source 
tarball.
+    + Run '''./configure --prefix=$PREFIX''' (Git users: '''./autogen.sh --prefix=$PREFIX''').
+    + Run '''make &amp;&amp; make install'''.
+    + Change to their directory.
+    + Save your work (backup your working files or do '''git stash''').
+    + Run '''git clean -xdf''' or drop the contents of the workspace except the .git folder or the source 
tarball.
+    + Run '''./configure --prefix=$PREFIX''' (Git users: '''./autogen.sh --prefix=$PREFIX''').
+    + Run '''make &amp;&amp; make install'''.
+* Change to their directory.
+* Save your work (backup your working files or do '''git stash''').
+* Run '''git clean -xdf''' or drop the contents of the workspace except the .git folder or the source 
tarball.
+* Run '''./configure --prefix=$PREFIX''' (Git users: '''./autogen.sh --prefix=$PREFIX''').
+* Run '''make &amp;&amp; make install'''.
+
+Some more information on building can be found at [[Hacking:Building| the building tutorials]].
+
+
+
+
+
+#### GIMP build breaks for missing dependency gegl-0.2 &gt; 0.2.0
+
+'''Problem: Building GIMP fails with a message, that the dependency gegl-0.2 &gt; 0.2.0 is not met. But in 
$prefix I see the GEGL files, for instance gegl-0.3.pc in $prefix/lib/pkgconfig.'''
+'''Cause:'''
+You have mismatched the versions:
+
+GIMP 2.8 needs GEGL from the branch gegl-0-2.
+
+GIMP 2.9 (=master) needs GEGL from the branch master.
+
+Obviously you have mixed GIMP 2.8 with GEGL master.
+
+'''Solution:'''
+
+If you want to build GIMP 2.8:
+
+
+* In GEGLs build directory run '''make uninstall'''.
+* For GEGL checkout gegl-0-2, run '''make''' and '''make install'''.
+* Go to the GIMP build directory and run '''autogen.sh''' again, run '''make''' and '''make install'''.
+
+If you want to build GIMP master:
+
+
+* In GIMPs workspace run 'git checkout master'.
+* Run '''autogen.sh''' again, run '''make''' and '''make install'''.
+
+#### Building development GIMP 2.99 breaks for missing dependency gegl-0.4 &gt; 0.4.xx
+
+'''Problem: Building the development version of GIMP (2.99) fails with a message that the dependency 
gegl-0.4 &gt; 0.4.xx is not met.'''
+'''Cause:'''
+
+To build the development version of GIMP (2.99) often requires the development version (bleeding edge) GEGL. 
 In other words, the GIMP unstable version can depend on the GEGL unstable version.
+
+Cloning the GEGL repository will get the development version of GEGL.  (But the latest commit may not be 
tagged yet in the repository, so you can't ask git for the tagged commit.  The meson.build file in the 
repository will usually show the *next* version that gegl.org will soon tag and release as stable.)
+
+Tagged versions of GEGL are captured by gimp.org in a tarball at [https://download.gimp.org/pub/gegl/0.4/ 
https://download.gimp.org/pub/gegl/0.4/], but not always the unstable, development version that a build of 
unstable GIMP requires.
+
+'''Solution:'''
+
+After you have downloaded, built, and installed gegl, to check the installed version, run: `pkg-config 
gegl-0.4 --modversion`
+
+#### Configure fails with a syntax error near unexpected token `x11,'
+
+'''Problem: configure fails with a message about a syntax error but there's no obvious syntax error.'''
+
+Example:
+
+```sh
+./configure: line 22865: syntax error near unexpected token `x11,'
+./configure: line 22865: `GTK_CHECK_BACKEND(x11, gtk_required_version,'
+```
+
+'''Cause:'''
+You're missing /usr/share/aclocal/gtk-3.0.m4, which is part of the GTK3 development package.
+
+'''Solution:'''
+Make sure you have libgtk-3-0 installed, including any associated -dev or -devel package.
+
+
+
+
+
+#### GIMP build fails for missing BABL function
+
+'''Problem: GIMP build fails for missing BABL function'''
+
+Example:
+
+```sh
+  /home/Workspace/gimp/app/core/libappcore.a(gimphistogram.o): In function `gimp_histogram_calculate':
+  /home/Workspace/gimp/app/core/gimphistogram.c:261: undefined reference to `babl_format_get_model'
+   operations/libappoperations.a(gimpoperationmaskcomponents.o): In function 
`gimp_operation_mask_components_prepare':
+  /home/Workspace/gimp/app/operations/gimpoperationmaskcomponents.c:150: undefined reference to 
`babl_format_get_model'
+  gegl/libappgegl.a(gimp-babl.o): In function `gimp_babl_format_get_base_type':
+  /home/Workspace/gimp/app/gegl/gimp-babl.c:361: undefined reference to `babl_format_get_model'
+  gegl/libappgegl.a(gimp-babl.o): In function `gimp_babl_format_get_linear':
+  /home/Workspace/gimp/app/gegl/gimp-babl.c:454: undefined reference to `babl_format_get_model'
+  gegl/libappgegl.a(gimp-babl-compat.o): In function `gimp_babl_format_get_image_type':
+  /home/Workspace/gimp/app/gegl/gimp-babl-compat.c:38: undefined reference to `babl_format_get_model'
+  collect2: error: ld returned 1 exit status
+```
+
+'''Cause:'''
+
+You have an older version of babl installed on your system, either in your local installation prefix
+or by a package. In this case the package libbabl-dev 0.1.10-1 was installed. Although the build environment
+variables were set to rely on the local installation prefix, the linker checked this old version and failed 
for
+not finding the symbol `babl_format_get_model` in BABL.
+
+'''Solution:'''
+
+* Check the file '''$prefix/lib/pkgconfig/babl.pc'''. If you find a line with 'Version: 0.1.10' or older, 
then your BABL library is too old. In this case, goto step 2, otherwise to step 4.
+* Change into your BABL source directory. Fetch the latest BABL source code, i.e. from git (branch 'master').
+* Clean and rebuild BABL from scratch: run '''autogen.sh''' or '''config''', '''make clean &amp;&amp; make 
uninstall &amp;&amp; make &amp;&amp; make install'''
+* In your package manager check the version of the BABL development library (on Debian systems: libbabl-dev, 
on Mandriva: libbabl-devel, on Red Hat systems:babl*src, on openSuSE systems:babl-devel). If you find version 
0.1.10 or older, then your BABL library is too old. In your package manager remove it completely and also the 
GEGL development package depending on it.
+* Also clean and rebuild GEGL from scratch to avoid version mismatch between GEGL and GIMP.
+* Clean and rebuild GIMP from scratch.
+
+#### Build of GIMP master fails in gimpcursor.c
+
+'''Problem: Build of GIMP master fails in gimpcursor.c'''
+
+Error messages:
+
+```sh
+/home/Workspace/gimp/app/widgets/gimpcursor.c:90:5: error: ‘cursor_corner_top’ undeclared here (not in a 
function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:98:5: error: ‘cursor_corner_right’ undeclared here (not in a 
function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:106:5: error: ‘cursor_corner_bottom’ undeclared here (not in a 
function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:114:5: error: ‘cursor_corner_left’ undeclared here (not in a 
function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:126:5: error: ‘cursor_side_top_right’ undeclared here (not in 
a function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:134:5: error: ‘cursor_side_bottom_right’ undeclared here (not 
in a function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:142:5: error: ‘cursor_side_bottom_left’ undeclared here (not 
in a function)
+/home/Workspace/gimp/app/widgets/gimpcursor.c:150:5: error: ‘cursor_side_top_left’ undeclared here (not in a 
function)
+```
+
+'''Cause:'''
+
+It's probably a gdk-pixbuf issue. It is for instance known to update the system loaders cache instead the 
cache of its local installation, if it's installed in a prefix which is in the PATH variable.
+
+'''Workarounds:'''
+''Workaround A (the short tour):''
+
+* '''cd cursors'''
+* '''make clean'''
+* '''cd ..'''
+* '''make'''
+
+
+''Workaround B (the big tour):''
+
+* '''gdk-pixbuf-query-loaders --update-cache''' (in case this doesnt work run it with sudo)
+* add the Pkgconfigpath of libgdk-pixbuf2.0-dev to the PKG_CONFIG_PATH environment variable
+* '''configure/autogen''' with your prefix
+* '''make clean'''
+* '''make'''
+
+
+Anyway, these are just workarounds. If you know the cause and a proper solution, feel free to edit this 
article.
+
+#### Errors on linking a static library, for instance with MinGW
+
+'''Problem: Errors on linking a static library, for instance with MinGW'''
+
+Compiling GIMP fails, because of not finding a library which is actually there (for instance gexiv2).
+
+The output of <code>make V=1</code> produces a message like this:
+
+```sh
+*** Warning: This system can not link to static lib archive
+/$your_workspace/share/crossroad/roads/w64/lib/libgexiv2.la.
+*** I have the capability to make that library automatically link in when
+*** you link to this library.  But I can only do this if you have a
+*** shared version of the library, which you do not appear to have.
+```
+
+'''Cause:'''
+
+You have not a shared (=dynamic) binary version, but a static binary of that particular library. Linking 
static binaries of most libraries is not supported by GIMP.
+
+You can recognize this by the file file extensions:
+
+Dynamic libraries have the extensions: '''so''' on Linux, '''dylib''' on OS X, '''dll''' on Windows.
+
+Static libraries have the extensions: '''a''' on Linux and OS X, '''lib''' on Windows.
+
+'''Solution:'''
+
+1. Get a dynamic binary version of that library. Either the package manager of your distribution or the web 
holds one or you
+have to compile it yourself.
+
+2. Compile GIMP again (starting with <code>configure</code> or <code>autogen.sh</code> to let the Autotools 
find the new library and make it included.)
+
+#### GIMP build fails with message 'Couldn't recognize the image file format for file ./cursor-bad.png'
+
+'''Problem: Building GIMP fails with message 'Couldn't recognize the image file format for file 
./cursor-bad.png' '''
+
+The whole message is
+
+```sh
+Making all in cursors
+make[2]: Entering directory `$your_workspace/gimp/cursors'
+  GEN    tool-cursors.list
+  GEN    gimp-tool-cursors.h
+
+failed to load "./cursor-bad.png": Couldn't recognize the image file format for file './cursor-bad.png'
+```
+
+'''Cause:'''
+
+The environment variable XDG_DATA_DIRS is modified in your build environment, which confuses the GLib 
library (GDK-Pixbuf).
+
+'''Solution:'''
+
+* Don't modify the environment variable XDG_DATA_DIRS in your build environment. I.e. if you build from a 
build script, don't set this variable there.
+* make distclean
+* autogen.sh or configure
+* make
+* make install
+
+#### GIMP master refuses to start with error 'GIMP requires the GEGL operation "gegl:alien-map"'
+
+'''Problem:'''
+GIMP master refuses to start and instead shows this error message (or similar, the name might be other than 
"alien-map")
+
+'GEGL operation missing!
+
+GIMP requires the GEGL operation "gegl:alien-map".
+This operation cannot be found. Check your
+GEGL install and ensure it has been compiled
+with any dependencies required for GIMP.'
+
+'''Cause:'''
+
+You have GEGL 0.2 installed on your system, but GIMP master requires GEGL master. Or you have GEGL master 
installed in your GIMP prefix, but GIMP fails to find it.
+Master means the latest version of the branch named "master" in the GEGL repository.  In other words, the 
GIMP project "tracks" the GEGL project.
+
+The GEGL version changes.  As of this writing, GIMP 2.99 uses gegl-0.4, but that may change in the future.
+
+'''Solution:'''
+
+To tell GIMP master where GEGL master is run
+
+'''export GEGL_PATH=${INSTALL_PREFIX}/lib/gegl-0.3'''
+
+before starting GIMP.
+
+To avoid a similar version mismatch with Babl, you can also run
+
+'''export BABL_PATH=${INSTALL_PREFIX}/lib/babl-0.1'''
+
+before starting GIMP.
+
+Details: at startup, GIMP checks the GEGL library for the presence of a certain set of GEGL operations.
+The operations are present as string literals in the binary.  You can test whether your GEGL library 
contains an operation using e.g.:
+
+'''grep -R "gegl:alien-map" /usr/local/lib/gegl-04'''
+
+#### Unit tests fail
+
+'''Problem:'''
+
+Many unit tests fail with an output similar to this:
+
+```sh
+FAIL: test-save-and-export
+#### ==================
+
+Xlib:  extension "RANDR" missing on display ":99".
+GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-save-and-export:15852): 
Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead.
+
+FAIL: test-session-2-6-compatibility
+#### ============================
+
+Xlib:  extension "RANDR" missing on display ":99".
+/gimp-session-2-6-compatibility/read_and_write_session_files: GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-session-2-6-compatibility:16107):
 Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead.
+
+FAIL: test-session-2-8-compatibility-multi-window
+#### =========================================
+
+Xlib:  extension "RANDR" missing on display ":99".
+/gimp-session-2-8-compatibility-multi-window/read_and_write_session_files: GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-session-2-8-compatibility-multi-window:16351):
 Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead.
+
+FAIL: test-session-2-8-compatibility-single-window
+#### ==========================================
+
+Xlib:  extension "RANDR" missing on display ":99".
+/gimp-session-2-8-compatibility-single-window/read_and_write_session_files: GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-session-2-8-compatibility-single-window:16595):
 Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead.
+
+FAIL: test-single-window-mode
+#### =====================
+
+Xlib:  extension "RANDR" missing on display ":99".
+GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-single-window-mode:16839): 
Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead.
+
+FAIL: test-tools
+#### ========
+
+Xlib:  extension "RANDR" missing on display ":99".
+GIMP-Error: Could not open 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/../app/tests/gimpdir/themerc' for writing: 
Permission denied
+
+GIMP-Error: Failed to open file 
'/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_inst/etc/gimp/2.0/templaterc': open() failed: No such 
file or directory
+
+
+(/var/lib/jenkins/workspace/gimp-master/gimp-2.9.1/_build/app/tests/.libs/lt-test-tools:17083): 
Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead
+```
+
+'''Cause:'''
+
+Look at the last error line for each failing test and start your research there.
+
+'''Solution:'''
+
+In case of
+''Gimp-Widgets-WARNING **: GDK returned bogus values for the monitor resolution, using 96 dpi instead'':
+
+The function '''g_warning''' was used for an error other than a programming error. Use the ''g_printerr'' 
function instead. See also 
[https://git.gnome.org/browse/gimp/commit/?id=a07f2301bbdf44ef00fba738f2ba157cd3546e39 commit a07f230 on GIMP 
master]
+
+#### Meson build yields error message: 'meson.build:1:0: ERROR: Value never is not boolean (true or false).'
+
+'''Problem:'''
+As above, or 'Value always is not boolean'
+
+'''Cause:'''
+
+You have used 'never' or 'always' in the build options of the meson command e.g. '-Djavascript=never'
+
+'''Solution:'''
+
+Use 'true' or 'false'.  Since about mid 2020.
+
+#### Meson build hangs i.e. never finishes
+
+'''Problem:'''
+
+In the console where you started the meson build, near the end of the build process, meson stops emitting 
messages and the command line prompt never comes back.
+
+'''Cause:'''
+
+Some step in the build did not complete.
+The default for meson is '-j 3', meaning build in parallel, so the last step shown in the console might not 
be the step that hung.
+
+'''Solution:'''
+
+Use 'ps -ef' to determine which process is hung, and debug that build step.
+Sometimes it is the g-ir-scanner tool.
+Or use '-j 1' so that the last step shown is the step that hung.
+
+#### build configure step stops: missing gtk-encode-symbolic-svg
+
+'''Problem:'''
+The executable tool gtk-encode-symbolic-svg could not be found.
+
+'''Cause:'''
+
+You have not installed the package containing the tool.
+
+'''Solution:'''
+
+Use tools provided by your distribution to find which package contains gtk-encode-symbolic-svg, and install 
that package.
+Since Ubuntu 20.04 focal, the tool gtk-encode-symbolic-svg is in Ubuntu package libgtk-3-bin.
+Formerly in Ubuntu package gtk-3-examples.
+
+### Jenkins
+
+#### The compiler fails for a missing directory, although that directory exists
+
+'''Problem: The compiler fails for a missing directory, although that directory exists'''
+
+The file config.log contains the lines
+
+```sh
+configure:3796: checking whether the C compiler works
+configure:3818: gcc ... "-L/usr/lib/x86_64-linux-gnu" ...  &gt;&amp;5
+gcc: error: "-L: No such file or directory
+gcc: error: /usr/lib/x86_64-linux-gnu": No such file or directory
+```
+
+'''Cause:'''
+
+In Jenkins' global configuration you set the environment variable LDFLAGS="-L/usr/lib/x86_64-linux-gnu".
+
+The quotes are not necessary here.
+
+'''Solution:'''
+
+Remove the quotes, save the global configuration and restart the job.
+
+If the environment variable PKG_CONFIG_PATH also contains that directory, you can omit it in LDFLAGS.
+
+#### Jenkins cannot access the Git repository
+
+'''Problem: Jenkins cannot access the Git repository'''
+
+The console log contains the lines:
+
+```sh
+stderr: fatal: unable to connect to git.gnome.org:
+git.gnome.org[...]: errno=Connection timed out
+```
+
+'''Cause:'''
+
+The Gnome Git server is down for maintenance.
+
+'''Solution:'''
+
+Try again later.
+
+### JHBuild
+
+#### JHBuild ignores autogenargs
+
+'''Problem:'''
+JHBuild ignores the '''autogenargs''' parameter for a target.
+
+'''Cause:'''
+A simple typo. In this case it ended with duplicated quotes and was after the closing bracket of the 
autotools tag.
+
+'''Solution:'''
+
+* Use the proper syntax: <autotools ....="" autogenargs="...">
+</autotools>
+* If the options in the JHBuild menu on the command line don't help, cancel the JHBuild process (option 
'3'-give up on module') and run it again.
+
+### See also
+
+* [Autotools questions at 
Stackoverflow.com](http://stackoverflow.com/questions/tagged/autotools?sort=frequent&amp;pageSize=15)
+
+* [Clang users mailing list](http://lists.cs.uiuc.edu/mailman/listinfo/cfe-users)
+* [Clang and LLVM questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/clang+or+llvm)
+
+* [The GCC-Help mailing list](http://gcc.gnu.org/ml/gcc-help/)
+* [GCC questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/gcc)
+
+* [GEGL Developer mailing list](https://mail.gnome.org/archives/gegl-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gegl" rel="nofollow">GEGL IRC channel</a>
+
+* [GIMP Developer mailing list](https://mail.gnome.org/archives/gimp-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gimp" rel="nofollow">GIMP IRC channel</a>
+
+* [Jenkins mailing lists](http://jenkins-ci.org/content/mailing-lists)
+
+## Code
+
+### Eclipse
+
+#### Menu items 'Reconfigure' and 'Autotools/...' are disabled
+
+'''Problem: When right-clicking on a CDT project, the item Reconfigure and the items in the Autotools 
submenu are disabled '''
+'''Problem: Reconfiguring a project ends with an error 'The chosen operation is not enabled' '''
+
+Neither cleaning or make distclean bring them back.
+
+'''Cause:'''
+Your project configuration is perhaps garbled.
+
+'''Solution:'''
+'''Alt. A'''
+
+In a terminal window change to the project's workspace folder, enter '''make distclean''' and 
'''./autogen.sh''' resp. '''./configure''' . Every time you want to reconfigure your project repeat this 
step. Subsequently building the project in Eclipse works despite the disabled Reconfigure/Autotools menu 
items.
+
+'''Alt. B'''
+
+* Delete the project (but '''don't tick''' 'Delete project contents on disk (cannot be undone)'!!)
+* Create the project again: Makefile project from existing sources, then New/Convert to Autotools project
+* In the project's properties configure the Autotools, Paths and Symbols (Include Path, Referenced projects)
+
+#### Reconfigure fails with message 'aclocal: error: non-option arguments are not accepted: '-I'
+
+'''Problem: Reconfiguring a CDT Autotools project causes error 'aclocal: error: non-option arguments are not 
accepted: '-I' '''
+'''Cause:'''
+In the global or project specific environments settings the ACLOCAL_FLAGS variable is embraced with quotes 
and Eclipse somehow can't handle this.
+
+'''Solution:'''
+
+* Edit the project's environments settings (Properties/ C/C++ Build / Environment). If the ACLOCAL_FLAGS 
variable doesn't appear here or is not printed boldly, then cancel that dialog and edit them in Window / 
Preferences / C/C++ Build / Environment).
+* Remove the quotes from the ACLOCAL_FLAGS variable.
+
+#### Basic tools not found although there
+
+'''Problem: Trying to build, clean or reconfigure the project ends with an error, that either sh, make, gcc 
or g++ could not be found although they are there.'''
+'''Cause:'''
+Eclipse doesn't find them in the PATH variable. Either you didn't include ${PATH} in your PATH settings or 
you included it, but Eclipse doesn't resolve it.
+
+'''Solution:'''
+
+* Edit the project's environments settings (Properties/ C/C++ Build / Environment). If the PATH variable 
doesn't appear here or is not printed boldly, then cancel that dialog and edit them in Window / Preferences / 
C/C++ Build / Environment).
+* Make sure your PATH variable setting contains the string ':${PATH}'. It must have the curly braces around 
it! If the variable is already there and isn't resolved anyway, then get its value from your operating system 
and replace ${PATH} with that value.
+
+#### Eclipse doesn't recognize CDT/Autotools project anymore
+
+'''Problem: After starting Eclipse has closed my CDT project. When trying to reopen it I get the message 
'The project description file (.project) for '${My project}' is missing.  This file contains important 
information about the project.  The project will not function properly until this file is restored.''''
+'''Problem: Eclipse tells in the project's properties that the project is not a CDT project (anymore).'''
+'''Cause:'''
+Eclipse's projects settings got lost. One candidate is having run 'git clean -xdf' in the workspace (in the 
first case when
+
+'''Solution:'''
+If you have a backup of the files .project, .cproject, .autotools, then restore them now to the project's 
folder. If you don't have them at hand:
+
+* Create a new dummy C project and convert it to an Autotools C project (New/CDT/Convert to Autotools 
project).
+* Copy the files .project, .cproject, .autotools from that project's folder into the folder of your damaged 
project.
+* Edit the projects CDT or Autotools settings.
+* Create a backup of the files .project, .cproject, .autotools.
+
+### See also
+
+* [Eclipse CDT support site](http://eclipse.org/cdt/support.php)
+* [Eclipse CDT questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/cdt)
+
+* [Emacs support](https://www.gnu.org/software/emacs/#HelpMailing)
+* [Emacs questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/emacs)
+
+* [Geany FAQ](http://www.geany.org/Documentation/FAQ)
+* [Geany questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/geany)
+
+* [GEdit support](https://wiki.gnome.org/Apps/Gedit)
+* [GEdit questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/gedit)
+
+* [GEGL Developer mailing list](https://mail.gnome.org/archives/gegl-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gegl" rel="nofollow">GEGL IRC channel</a>
+
+* [GIMP Developer mailing list](https://mail.gnome.org/archives/gimp-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gimp" rel="nofollow">GIMP IRC channel</a>
+
+* [Netbeans mailing lists and forums](https://netbeans.org/community/lists/index.html)
+* [Netbeans questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/netbeans)
+
+* [Basic vi commands](http://www.cs.colostate.edu/helpdocs/vi.html)
+* [Vi questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/vi)
+
+## Debug
+
+### See also
+
+* <a class="external text" href="irc://irc.freenode.net:6667/#gdb" rel="nofollow">GDB IRC channel</a>
+* [GDB wiki](http://sourceware.org/gdb/wiki/)
+* [GDB questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/gdb)
+
+* [GEGL Developer mailing list](https://mail.gnome.org/archives/gegl-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gegl" rel="nofollow">GEGL IRC channel</a>
+
+* [GIMP Developer mailing list](https://mail.gnome.org/archives/gimp-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gimp" rel="nofollow">GIMP IRC channel</a>
+
+* [LLDB questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/lldb)
+
+## Manage versions
+
+### Git
+
+#### I'm a few commits behind
+
+'''Problem: After checking out a particular branch, Git tells me, that I'm a few commits behind,'''
+
+for example: 'Your branch is behind 'origin/gimp-2-8' by 2 commits, and can be fast-forwarded.'
+
+'''Cause:'''
+On '''git pull''' Git didn't update the HEAD on your local branch for whatever reason.
+
+'''Solution:'''
+Try '''git pull origin''' to update your local branch.
+
+#### Git marks untouched files as dirty
+
+'''Problem: git status shows that there are untracked files I haven't touched at all'''
+
+For instance this:
+
+```sh
+$:~/Workspace/gimp$ git status
+On Branch master
+
+Untracked files:
+
+       app/base/
+       app/composite/
+       app/paint-funcs/
+       plug-ins/file-xjt/
+       plug-ins/metadata/
+```
+
+These files are not in the current branch, but in another (for instance gimp-2-8).
+
+'''Cause:'''
+For some reasons a recent '''git checkout''' did not delete them. Now these zombies lie around to frighten 
poor developers.
+
+'''Solution:'''
+
+* Remove them from your disk.
+* If you noticed this error in your IDE then refresh your workspace there (in Eclipse: right click on your 
project, then click '''Refresh''').
+
+#### Pull error: 'Insufficient permission for adding an object to repository database .git/objects'
+
+'''Problem:'''
+On pulling Git shows me the aforementioned error.
+
+'''Cause:'''
+Permission issues in your file system.
+
+'''Solution:'''
+
+* Change into your directory where the project's .git folder resides. Usually this is the working directory.
+* On Linux or OS X run '''sudo chown -R gituser:gituser .git/objects''' (replace gituser with your user 
name). On Windows right click on the .git/objects folder, choose 'Properties', choose the 'Security' tab, 
click the 'Advanced' button, choose the 'Owner' tab, click the 'Edit...' button. Set the file owner for that 
folder and all files and subdirectories in it. See also the 
[http://www.techotopia.com/index.php/Understanding_Windows_Server_2008_File_and_Folder_Ownership_and_Permissions#Taking_and_Transferring_Windows_Server_2008_File_and_Folder_Ownership
 Techotopia tutorial]
+
+### Eclipse
+
+#### Eclipse marks untouched files as dirty
+
+'''Problem: Eclipse shows dirty files and folders I have never touched'''
+<a href="#Git_marks_untouched_files_as_dirty"> See the related Git error.</a>
+
+### See also
+
+* [Git documentation (man pages, reference manual, videos, links)](https://git-scm.com/doc)
+* [The Git online book](https://git-scm.com/book)
+* [Git community support](https://git-scm.com/community)
+* [Git questions at Stackoverflow.com](https://stackoverflow.com/questions/tagged/git)
+
+* [GIMP Developer mailing list](https://mail.gnome.org/archives/gimp-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gimp" rel="nofollow">GIMP IRC channel</a>
+* [GEGL Developer mailing list](https://mail.gnome.org/archives/gegl-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gegl" rel="nofollow">GEGL IRC channel</a>
+
+* [Eclipse EGit support site](https://eclipse.org/egit/support/)
+* [Eclipse JGit support site](https://www.eclipse.org/jgit/support/)
+* [Eclipse EGit questions at Stackoverflow.com](https://stackoverflow.com/questions/tagged/egit)
+
+## Translate
+
+#### Lots of merge conflicts in GIMP master
+
+'''Problem: I'm translating on the current production branch of GIMP (2-8 etc.) and on master. I'd like to 
cherry-pick my changes from the production branch to the master branch. But I get lots of merge conflicts and 
changes I never introduced.'''
+'''Cause:'''
+Cherry-picking translations from the production branch into the master branch doesn't work.
+
+'''Solution:'''
+Commit your translation updates directly into the master branch or try to merge your translation branch into 
the master branch.
+
+#### See also
+
+* [GEGL Developer mailing list](https://mail.gnome.org/archives/gegl-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gegl" rel="nofollow">GEGL IRC channel</a>
+
+* [GIMP Developer mailing list](https://mail.gnome.org/archives/gimp-developer-list/)
+* <a class="external text" href="irc://irc.gimp.org/#gimp" rel="nofollow">GIMP IRC channel</a>
+
+* [GNU gettext manual](http://www.gnu.org/software/gettext/manual/gettext.html)
+* [GNU gettext FAQ](http://www.gnu.org/software/gettext/FAQ.html)
+
+* [GNOME Translation project wiki](https://wiki.gnome.org/TranslationProject)
+
+* [Poedit support](http://www.poedit.net/support.php)
+* [Poedit questions at Stackoverflow.com](http://stackoverflow.com/questions/tagged/poedit)
+
+* [Virtaal documentation](http://docs.translatehouse.org/projects/virtaal/en/latest/)
+
+## Runtime Errors
+
+Warnings and errors displayed in a terminal/console in which you started GIMP from a command line.
+
+Many are just clutter, that make it hard to find severe errors from code you are testing.
+
+#### 'GEGL-Message: 14:09:17.687: Module '/usr/local/lib/x86_64-linux-gnu/libgegl-npd-0.4.so' load error: 
Missing gegl_module_query() symbol ?'
+
+'''Problem:'''
+GIMP starts, but the terminal displays many messages similar to the above, when plugins are loaded.
+It is not clear whether these messages affect functioning, they might just be annoying warnings.
+
+'''Cause:'''
+Missing environment variables.
+
+'''Solution:'''
+See above under 'Building'.  The environment variable GEGL_PATH must reference the top gegl directory, not 
just its parent.
+Referencing the parent is sufficient for GIMP to start, but not for plugins to load without these warnings.
+
+#### GIMP fails to start with error, 'GIMP requires the GEGL operation "gegl:alien-map"'
+
+'''Problem:'''
+GIMP starts fails to start, with the message above.
+
+'''Cause:'''
+Missing environment variables.
+
+'''Solution:'''
+See above under 'Building'
+
+#### A plugin fails to appear in the menus, with error like "GIMP-WARNING: gimp-2.xx: gimp_wire_read(): 
error"
+
+'''Problem:'''
+GIMP starts, but a plugin does not appear in the GIMP menus as expected, and the terminal shows the above 
message.
+
+'''Cause:'''
+At startup, GIMP searches certain directories for plugins (executables and interpretable text files) and 
"queries" them.
+This means it starts them in a separate process and then communicates with them over a 'wire' i.e. 
interprocess communication.
+If the plugin crashes or fails to respond, Gimp gives the error above.
+You probably installed a plugin that is fatally flawed.
+
+'''Solution:'''
+Remove the plugin.  To see which plugin to remove, start Gimp with the '--verbose' flag, and it will print 
the pathname of plugin files as it queries them.
+
+To debug the flawed plugin, you can use print statements.
+
+An interpreted plugin may fail very early in its text, for example in the hashbang i.e. '#!/usr/bin/env 
python' statement on the first line,
+or in an import statement.
+
+#### Chain of python exceptions beginning with gi.RepositoryError: Typelib file for namespace 'Gegl', 
version '0.4' not found
+
+'''Problem:'''
+On startup, GIMP starts but shows a long chain of Python exceptions.  The root exception (the first in the 
list) is as above.  Affects loading of plugins.
+
+'''Cause:'''
+Python is using GLib introspection, but can't find the typelibs for GIMP.  Typelibs are in a directory named 
girepository-1.0.  The GIMP typelib is named like "Gimp-3.0.typelib".
+
+'''Solution:'''
+Define environment variable GI_TYPELIB_PATH.  For example, export 
GI_TYPELIB_PATH=/usr/local/lib/x86_64-linux-gnu/girepository-1.0:/usr/local/lib/girepository-1.0  .  The 
example is for Ubuntu 19.10.  You may want to change the prefix of the paths, for example using the 
GIMP_PREFIX environment variable (if you use it.)
+
+The typelibs for GIMP, Gegl, and Babl might be on different paths (as in the example.)
+
+#### Gtk-Message: 19:04:46.797: Failed to load module "canberra-gtk-module"
+
+'''Problem:'''
+Terminal often displays message like above.  Does not affect operation, except sounds may be missing?
+
+'''Cause:'''
+Package libcanberra-gtk3-module is missing.
+
+'''Solution:'''
+Install missing package, for example:  sudo apt-get install libcanberra-gtk3-module
+
+#### (gimp-2.99:xx): dbind-WARNING **: 09:35:43.023: Couldn't register with accessibility bus:
+
+'''Problem:'''
+Terminal often shows message like above.  Does not affect operation, unless you need accessibility i.e. are 
visually or hearing impaired.
+
+'''Cause:'''
+Seems to be a long-standing bug in Linux distributions.
+
+'''Solution:'''
+In your environment, export NO_AT_BRIDGE=1
+
+#### luajit: ...mp/2.99/plug-ins/goat-exercise-lua/goat-exercise-lua.lua:22: module 'lgi' not found:
+
+'''Problem:'''
+On startup, terminal shows a message that begins like above and ends with "GIMP-WARNING: gimp-2.99: 
gimp_wire_read(): error".
+Affects loading of lua language plugins.
+In the development branch of GIMP, a set of "goat-exercise-foo" plugins exercise some GObject Introspection 
language bindings (C, Python, Lua, JS, Scheme, Perl ?)
+
+'''Cause:'''
+Package lua-lgi is missing.
+
+'''Solution:'''
+Install the package.
+
+## On Ubuntu:  Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed 
(error == NULL): Icon 'image-missing' not present in theme Symbolic (gtk-icon-theme-error-quark, 0====
+
+'''Problem:'''
+On Ubuntu (only?), when using a plugin that opens a Gtk3 file chooser widget, terminal shows a message as 
above, and plugin crashes.
+
+'''Cause:'''
+Package gnome-icon-theme is missing.  See [https://gitlab.gnome.org/GNOME/gimp/-/issues/2029 
https://gitlab.gnome.org/GNOME/gimp/-/issues/2029].
+
+'''Solution:'''
+Install the package. If you are not building Gimp yourself, apparently this issue is fixed by the packaging 
of Gimp having a dependency on package gnome-icon-theme.
+
+#### (gimp-2.99:xx): dconf-WARNING **: 13:59:42.430: failed to commit changes to dconf: Failed to execute 
child process ?dbus-launch? (No such file or directory)
+
+'''Problem:'''
+The message appears as you start a plugin.  It seems harmless unless you have configured GLib to stop on 
warnings, or if you want to use the services of [https://en.wikipedia.org/wiki/D-Bus dbus]
+'''Cause:'''
+This is a warning from GLib.  Gimp is usually built to support dbus (but can be configured without that 
support?)  The message means that when Gimp attempted to execute the command 'dbus-launch', it could not be 
found on the system.
+
+'''Solution:'''
+Install package dbug-x11, or whichever package contains the executable command dbus-launch.
+
+## Templates
+
+#### Template for investigated solutions
+
+'''Problem:'''
+'''Cause:'''
+'''Solution:'''
+
+#### Template for workarounds
+
+'''Problem:'''
+'''Workaround:'''
+
+Anyway, this is just a workaround. If you know the cause and a proper solution, feel free to edit this 
posting.
diff --git a/content/core/setup/build/Windows.md b/content/core/setup/build/Windows.md
index 6460e05..411ae5d 100644
--- a/content/core/setup/build/Windows.md
+++ b/content/core/setup/build/Windows.md
@@ -5,12 +5,11 @@ Date: 2021-08-30
 weight: 3
 ---
 
-The main GIMP building instructions are at [[Hacking:Building]]. This page is for Windows-specific additions 
to that page.
+The main GIMP building instructions are at [Building GIMP](../). This page is for Windows-specific additions 
to that page.
 
 Note: the instructions are not always kept up to date. The primary development platform is the Debian 
Testing GNU/Linux distribution, so the very latest code from Git might not always build on other platforms.
 
 
-
 ## Building GIMP natively under Windows using MSYS2
 
 Msys2 is a POSIX environment with basically everything you would find on a Linux system (shell, package 
manager, GCC…). It allows to use POSIX tools to build Windows softwares.
@@ -187,7 +186,7 @@ Simply hit enter at the prompts for which packages to install (default=all). Thi
 
 ### Building the software
 
-You can now just follow the instruction on the main page [[Hacking:Building]]. Just be careful of the 
following changes :
+You can now just follow the instruction on the main page [Building GIMP](../). Just be careful of the 
following changes:
 
 <pre>export GIMP_PREFIX=`realpath ~/gimp_prefix`
 export PATH="$GIMP_PREFIX/bin:$PATH"
@@ -197,6 +196,7 @@ export LD_LIBRARY_PATH="$GIMP_PREFIX/lib:$LD_LIBRARY_PATH"
 </pre>
 
 * If you are on Windows 64bits, you need to add mingw64 on 32bits mingw32
+
 <pre>#environment variable for Autotools
 export ACLOCAL_FLAGS="-I/c/msys64/mingw64/share/aclocal"
 #environment variable for introspection
@@ -204,7 +204,7 @@ export XDG_DATA_DIRS="$XDG_DATA_DIRS:$GIMP_PREFIX/share:/usr/local/share/:/usr/s
 </pre>
 
 
-You can add all the environment variable on C:\msys64_or_msys32\home\{USERNAME}\.bash_profile then run
+You can add all the environment variable on `C:\msys64_or_msys32\home\{USERNAME}\.bash_profile` then run
 
 <pre>. .bash_profile
 </pre>
@@ -216,7 +216,7 @@ You can add all the environment variable on C:\msys64_or_msys32\home\{USERNAME}\
 * Disable docs for Gegl : <code>-Ddocs=false</code> while calling Meson.
 
 
-You may want to disable the docs while building Gimp :
+You may want to disable the docs while building GIMP :
 
 
 * Meson build : <code>-Dgtk-doc=false -Dgtk-doc-app=false</code>
@@ -224,9 +224,9 @@ You may want to disable the docs while building Gimp :
 
 ## Cross-Compiling GIMP under UNIX using crossroad
 
-A tool named [https://pypi.python.org/pypi/crossroad crossroad] has been developed to cross-build for 
Windows under Linux (it was even originally started to crossbuild GIMP specifically).
+A tool named [crossroad](https://pypi.python.org/pypi/crossroad)  has been developed to cross-build for 
Windows under Linux (it was even originally started to crossbuild GIMP specifically).
 
-See the [http://girinstud.io/news/2016/05/crossroad-0-6-released-cross-building-gimp-as-an-example/ tutorial 
explaining how to build GIMP with it].
+See the [tutorial explaining how to build GIMP with 
it](http://girinstud.io/news/2016/05/crossroad-0-6-released-cross-building-gimp-as-an-example/).
 
 Condensed, here is the process:
 
@@ -269,13 +269,6 @@ crossroad install \
     libwmf-devel \
     libgexiv2-devel headers
 
-wget [http://prdownloads.sourceforge.net/libpng/libpng-1.6.29.tar.xz 
http://prdownloads.sourceforge.net/libpng/libpng-1.6.29.tar.xz]
-tar xf libpng-1.6.29.tar.xz
-pushd libpng-1.6.29
-crossroad configure
-make &amp;&amp; make install
-popd
-
 git clone <a class="external free" href="git://git.gnome.org/babl" 
rel="nofollow">git://git.gnome.org/babl</a>
 pushd babl
 crossroad configure
@@ -313,7 +306,7 @@ NOTE: the following procedure should be distribution-independent and does not re
 
 Has been known to work on at least: Linux Mint 15, Ubuntu 12.04LST and Mageia 2 distributions.
 
-''Source of the original procedure from an 
[https://mail.gnome.org/archives/gimp-developer-list/2012-May/msg00067.html email by Victor Oliveira].''
+''Source of the original procedure from an [email by Victor 
Oliveira](https://mail.gnome.org/archives/gimp-developer-list/2012-May/msg00067.html).''
 
 
 ### Install mingw-w64
@@ -331,9 +324,9 @@ The archive contains a prefix tree, that you can consider as read-only (just lik
 
 The default environment provided by MinGW does not have the huge list of dependencies that GIMP requires.
 
-Fortunately the [https://mail.gnome.org/archives/gimp-developer-list/2012-May/msg00067.html email] linked 
above has bash script named '''grab-stuff.sh''' (which calls itself a python3 script named 
"download-mingw-rpm.py", so you have to download both and have python3), which downloads pre-compiled version 
of all needed dependencies for cross-compiling (it uses OpenSuse repositories as source, but it does not mean 
at all you need rpm support).
+Fortunately the [email](https://mail.gnome.org/archives/gimp-developer-list/2012-May/msg00067.html) linked 
above has bash script named `grab-stuff.sh` (which calls itself a python3 script named 
`download-mingw-rpm.py`, so you have to download both and have python3), which downloads pre-compiled version 
of all needed dependencies for cross-compiling (it uses OpenSuse repositories as source, but it does not mean 
at all you need rpm support).
 
-From the root of your cross-compiling prefix ($HOME/w64) run:
+From the root of your cross-compiling prefix (`$HOME/w64`) run:
 
 <pre>bash grab-stuff.sh
 </pre>
@@ -342,7 +335,6 @@ You will notice in particular a new usr/ folder, and inside i686-w64-mingw32/ an
 
 TODO : Make a proper dependency list.
 
-
 ### Set your cross-compiling environment
 
 Define the environment variables as described in [[Hacking:Building]]. You may also need to reset pkg-config:
diff --git a/content/core/setup/build/_index.md b/content/core/setup/build/_index.md
index 09a6073..af59ecb 100644
--- a/content/core/setup/build/_index.md
+++ b/content/core/setup/build/_index.md
@@ -278,7 +278,7 @@ You can customize the directory where GIMP stores settings. This prevents any in
 
 Most problems will occur during the configure stage, and with any luck it's just a missing package and the 
error message will make it clear what package you need. But there are more subtle problems that can occur. If 
you have a difficult error, look in:
 
-[[Hacking:Problems_and_solutions]]
+[Problems and Solutions](problems_and_solutions)
 
 ## Running Your New GIMP
 
diff --git a/content/core/setup/build/macOS.md b/content/core/setup/build/macOS.md
index fd2814e..d75ee3b 100644
--- a/content/core/setup/build/macOS.md
+++ b/content/core/setup/build/macOS.md
@@ -13,4 +13,4 @@ GIMP has an official build whose scripts are located at this repo: https://gitla
 
 Some older links explain how to build and install GIMP on an Apple computer running the OSX operating 
system. We are not sure how acceptable they are with current code.
 
-One person describes [how to build Gimp on 
OSX](http://sites.google.com/site/httimchen/2011_imagesvn/build-gimp-on-mac) using native 
[gtk-osx](http://gtk-osx.sourceforge.net/)  and the [jhbuild](http://developer.gnome.org/jhbuild/)  tool.
+One person describes [how to build GIMP on 
OSX](http://sites.google.com/site/httimchen/2011_imagesvn/build-gimp-on-mac) using native 
[gtk-osx](http://gtk-osx.sourceforge.net/)  and the [jhbuild](http://developer.gnome.org/jhbuild/)  tool.
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