This function sets the refresh callback of the specified window, which is called when the content area of the window needs to be redrawn, for example if the window has been exposed after having been covered by another window.
On compositing window systems such as Aero, Compiz, Aqua or Wayland, where the window contents are saved off-screen, this callback may be called only very infrequently or never at all.
This function sets the refresh callback of the specified window, which is called when the content area of the window needs to be redrawn, for example if the window has been exposed after having been covered by another window.
On compositing window systems such as Aero, Compiz, Aqua or Wayland, where the window contents are saved off-screen, this callback may be called only very infrequently or never at all.