[GtkGLExt] new Gtk3-openGl-binding

[fwork <franz reiter cadcam co at>]

Since gtk-2.20 a OpenGL-redraw sometimes clears all parent-widgets;
with gtkglarea and with gtkglext and also direct into a
gtk_drawing_area_new, on Linux and Windows.  
See Bugzilla-bugs 626751 and 645208.
This problem also exists with gtk3.
So we have tried to make a new opengl-binding, with a own
toplevel-window for OpenGL and direct with glx.
The project is Gtk-Toolbox-2.00 (GPL); see
http://www.gcad3d.org/gui_gtk/devdoc/index.htm
This solves the problem of clearing all parent widgets.
But this problem exists:
 The OpenGL-window lies exactly over an paned-window,
 but the Window does not resize before idle starts.

This means, Opengl works well in the new window, but we could not yet
solve the (pure Gtk-problem) of resizing the toplevel-window before
idle.

The files are:
http://www.gcad3d.org/gui_gtk/gtk_opengl_v2.c
http://www.gcad3d.org/gui_gtk/tst_gui_gl2.c

Please help if you have ideas ..

regards

Franz Reiter