As far as I can remember, this started happening when the fade animation was replaced with the busy cursor. This is probably just an extreemly minor usabilty papercut.
Unacceptable UI inconsitency, hot fix committed. commit 0c36903fb399f187e45f835a6a04a3be320fa122 Author: Kristian Høgsberg <krh@bitplanet.net> Date: Thu Feb 14 21:31:44 2013 -0500 shell: Add back ability to rotate unresponsive surfaces When a surface in deemed unresponsive and we trigger the busy cursor, it's no longer possible to rotate the surface. This is clearly unacceptable. This patch adds handling of right clicks to the busy grab so that we can continue to rotate a surface even if the client is sleeping. https://bugs.freedesktop.org/show_bug.cgi?id=60609
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