Vlad Zahorodnii authored Jul 20, 2020 and Vlad Zahorodnii committed Jul 22, 2020

If AbstractClient::setFrameGeometry() is called from a slot connected
directly to the frameGeometryChanged() signal, then is there a good
chance that kwin will fall into an infinite recursion. However, that's
the case with only X11 and internal clients.

The root cause of the infinite recursion is that both X11Client and
InternalClient compare the new geometry against the geometry before
update blocking. In order to fix the bug, we simply need to ensure that
updateGeometryBeforeUpdateBlocking() has been called before we start
emitting the frameGeometryChanged() signal.

Furthermore, a couple of tests were added to ensure that we won't hit
this subtle bug again.