Mutter 3.9.4 Tweaks Window Shadows

Among the new features implemented in Mutter 3.9.4, we can mention that the window shadows have been tweaked, as well as two new APIs, one to query if the stage is focused, and the other one to query the monitor for a given position. Mutter 3.9.4 also allows slicing of backgrounds to avoid texture size, ignores its own focus events for focus prediction, and no longer forces attached dialogs to be border-only.