void gtk_widget_set_double_buffered ( GtkWidget* widget, gboolean double_buffered )
Widgets are double buffered by default; you can use this function
to turn off the buffering. “Double buffered” simply means that
gdk_window_end_draw_frame() are called
automatically around expose events sent to the
gdk_window_begin_draw_frame() diverts all drawing to a widget’s
window to an offscreen buffer, and
gdk_window_end_draw_frame() draws the
buffer to the screen. The result is that users see the window
update in one smooth step, and don’t see individual graphics
primitives being rendered.
In very simple terms, double buffered widgets don’t flicker, so you would only use this function to turn off double buffering if you had special needs and really knew what you were doing.
Note: if you turn off double-buffering, you have to handle expose events, since even the clearing to the background color or pixmap will not happen automatically (as it is done in gdk_window_begin_draw_frame()).
In 3.10 GTK and GDK have been restructured for translucent drawing. Since then expose events for double-buffered widgets are culled into a single event to the toplevel GDK window. If you now unset double buffering, you will cause a separate rendering pass for every widget. This will likely cause rendering problems - in particular related to stacking - and usually increases rendering times significantly.
This function does not work under non-X11 backends or with non-native windows. It should not be used in newly written code.