[2 patches] Fix missing update when toggling client-side decorations / Avoid calling requestUpdate from wrong thread

When CSD is toggled while a window is showing, it would change the size and recreate the buffers, but since the widget area remained the same size, we would not trigger a redraw. The result was that when you got any update to the window, it would redraw the widgets that had changed, and the rest would be transparent.

Since this is a fairly specialized case, we fix it the simple way, by just issuing an extra update when it happens.

This also required an update to the surface test, since there is an additional buffer commit in the beginning of the sequence now.

Pick-to: 5.15 6.2 6.3 Fixes: QTBUG-95032 Change-Id: Ic4bdb9c66a2ea76546926dd622f2d2dac5dce10c Reviewed-by: Qt CI Bot qt_ci_bot@qt-project.org Reviewed-by: Liang Qi liang.qi@qt.io (cherry picked from commit af7b60ad)