WindowSetThemeEnabled window enable
This function tells a window if it should use the system's "theme" code to draw the windows' background instead if its own background drawing code. This does not always have any effect since the underlying platform obviously needs to support the notion of themes in user defined windows. One such platform is GTK+ where windows can have (very colorful) backgrounds defined by a user's selected theme.
Dialogs, notebook pages and the status bar have this flag set to true by default so that the default look and feel is simulated best.