This property, if present, indicates to any program which acts as a compositing manager that it SHOULD NOT change _NET_WM_WINDOW_OPACITY on this window and that it SHOULD NOT render the window at any opacity other than that given by _NET_WM_WINDOW_OPACITY (or, in its absence, fully opaque). It also indicates to any program which provides means of altering a window's opacity that it SHOULD NOT alter this window's opacity. Window managers acting as compositing managers MAY take this into account when displaying a window. Window managers MUST forward the value of this property to any enclosing frame window. This property MAY change while the window is mapped (though it is not normally expected to do so) and the window manager MUST respect changes while the window is mapped. Programs which provide means of altering a window's opacity MAY take this into account. Programs other than the owner of the window SHOULD NOT add or remove this property. Rationale: This property is intended to prevent a window manager from applying temporary effects when a window which is being used for some form of graphics hardware-assisted overlay, e.g. Xv or XvMC, is being moved or resized by the user, and to prevent alteration of the same window's opacity by programs other than the owner.