gdk:window-background-pattern (window)

window -- a gdk:window object
pattern -- a cairo:pattern-t pattern to use, or nil

The pattern to use for the background or nil to use the parent's background. The gdk:window-background-pattern function gets the pattern used to clear the background on the window. If the window does not have its own background and reuses the parent's, nil is returned and you will have to query it yourself. The (setf gdk:window-background-pattern) function sets the background of the window.

A background of nil means that the window will inherit its background form its parent window.

The windowing system will normally fill a window with its background when the window is obscured then exposed. The gdk:window-background-pattern function has been deprecated since version 3.22 and should not be used in newly written code. Do not use this function.