Gets a GdkGC with the given depth, colormap and GdkGCValues.
If a GdkGC with the given properties already exists then it is returned,
otherwise a new GdkGC is created.
The returned GdkGC should be released with gtk_gc_release() when it is no
longer needed.
Gets a GdkGC with the given depth, colormap and GdkGCValues. If a GdkGC with the given properties already exists then it is returned, otherwise a new GdkGC is created. The returned GdkGC should be released with gtk_gc_release() when it is no longer needed.