Some window managers can send garbage values during the initial mapping of a window, and need the position set again after mapping to ensure proper placement. Position requests sent before mapping can otherwise end up ignored. Ignore initial configure events when initially showing the window, and make sure that the position is set after the window is mapped, either when the window borders appear, or after the initial configure events in the case of borderless windows.
This also eliminates sending excessive/redundant move requests, which can cause strange behavior on some window managers, particularly if done before the window is actually mapped.
Fixes cases of incorrect initial window placement on GNOME + XWayland.
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