[gimp] app: in the prefs dialog, warn that OpenCL support is experimental

[Michael Natterer <mitch src gnome org>]

commit 7998a27b8b0fe993b4f82c3fe2fc747ece75f6f8
Author: Michael Natterer <mitch gimp org>
Date:   Mon Feb 4 10:38:43 2019 +0100

    app: in the prefs dialog, warn that OpenCL support is experimental

 app/dialogs/preferences-dialog.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/app/dialogs/preferences-dialog.c b/app/dialogs/preferences-dialog.c
index 51fe30a95a..fb37b506bb 100644
--- a/app/dialogs/preferences-dialog.c
+++ b/app/dialogs/preferences-dialog.c
@@ -1189,6 +1189,12 @@ prefs_dialog_new (Gimp       *gimp,
                           _("Use OpenCL"),
                           GTK_BOX (vbox2));
 
+  hbox = prefs_hint_box_new (GIMP_ICON_DIALOG_WARNING,
+                             _("OpenCL drivers and support are experimental, "
+                               "expect slowdowns and possible crashes "
+                               "(please report)."));
+  gtk_box_pack_start (GTK_BOX (vbox2), hbox, FALSE, FALSE, 0);
+
   /*  Image Thumbnails  */
   vbox2 = prefs_frame_new (_("Image Thumbnails"), GTK_CONTAINER (vbox), FALSE);