To create a GC, call the new_gc() method of a drawable. This method can also take an associative array specifying some initial values (only foreground, background, tile, stipple, and clip_mask are currently supported). The rest have to be set manually. new_gc(); or // create GC and set some fields $gc = $window->new_gc(array('foreground' => $fg_color, 'background' => $bg_color)); $gc->function = GDK_XOR; $gc->line_width = 3; $gc->cap_style = GDK_CAP_ROUND; ?>]]> Simply pass the GC to the drawing function that you need to use. Which GC fields are used for the drawing operation depends on the function. ]]>