pixmap_invert = gdk_pixmap_new(pixmap, w, h, 1);
GdkGC* gc = gdk_gc_new(pixmap_invert);
gdk_gc_set_function(gc, GDK_COPY_INVERT);
pixmap_invert = gdk_pixmap_new(pixmap, w, h, 1);
GdkGC* gc = gdk_gc_new(pixmap_invert);
gdk_gc_set_function(gc, GDK_COPY_INVERT);