Changes which stacking group the window is part of.
Background— Places the window behind normal windows, even when it has focus.
Normal— Restores the default stacking behavior, where the window is placed in front of other normal windows when it is focused, and is placed behind other normal windows when it loses focus.
Floating— Places the window in front of normal windows, even when it doesn’t have focus.
Keywords: above, back, background, backstop, below, desktop, floating, foreground, front, group, layer, lower, order, overlay, properties, raise, settings, stacking, topmost