UI elements in rviz under Xwayland fail to dock properly

rviz allows users to undock panels and re-dock them. When running under weston via XWayland this leads to multiple flavours of brokenness.

Once the initial drag completes, attempting the drag the window again crashes the compositor. (!972 (merged))

The window also jumps to a set location and, even when patched with !972 (merged), can never be moved again(#642)

The window can be redocked with a double click on its title bar, but after that point it never visibly updates again - though it does process input events (eg: you can toggle the visible "grid" in the main application window with it)