[Cmake] Moving from gtk1 to gtk2

[Jeff Holle]

I'm experimenting with the first project that uses cmake that I have
interest in (wxArt2D).

I've discovered bugs in it which switching to gtk2 instead of gtk1
"seems" to fix.

However, this isn't currently clear because wxArt2D's Cmake constructed
makefiles still use both gtk1 and glib1 include paths erroneously
(my wxWindows build didn't).

In manually altering a wxArt2D makefile I've succeeded in compiling a
significant module by making two types of chanages.

    1. Changing all references to gtk to gtk-2.0 and glib to glib-2.0.
    2. Adding numerous include paths that are subcomponents of either
gtk or glib.  This includes:  pango and atk.

I know how to add the later to this project, but don't understand why
gtk2 requires it while gtk1 (didn't?).

I don't know how to avoid gtk1 and glib1 instead of gtk2 and glib2
references.

I've attempted defining the GTK_INCLUDE_DIR environment variable as
"/usr/include/gtk-2.0/include", and various other values, with no success.

In addition, I modified FindGTK.cmake to first look in the gtk2 and
glib2 directorires.  I checked and these looked for files exist.  This
process wasn't successful either.

Any help would be appreciated.