New toolbar widget

[Brett Hall <swizin rain org>]

Attached is the header for a customizable toolbar widget.  I originally
started writing this for my own use but figured I would see if there was
any interest in adding it to Gtk+.  I don't know if it could actually
act as a replacement for the current toolbar widget since it is derived
from the current toolbar widget.  It is also a bit more complicated to
use than the current toolbar widget and probably isn't appropriate for
every application.  The full source is available at
http://www.rain.org/~swizin/custom_toolbar.tar.bz2 .  The source
distribution also includes a small test application that demonstrates
the use of the widget.  In a nutshell: any custom toolbars created can
have their contents modified by the user through drag and drop
operations.  The program using the toolbars must provide some way of
launching the toolbar customization widget (ie a menu option "customize
toolbars").  The customization widgets consists of a list of widgets
that can be placed on the toolbars (the program registers information
about the widgets when it starts up) a description of the currently
selected widget (extracted from the private part of the widget's
tooltip) and a trash area.  Widgets can be dragged from the list to the
position on the toolbar where the user would like it too be located.
Widgets already on the bar can also be dragged to new positions while
the customization widget is active.  Finally dragging widgets to the
trash removes them from the toolbar as one would expect.  The test
application included with the source demonstrates all of this.
-brett

custom_toolbar.h.bz2