Without setting the property, Plasma's panel and dialogs lose the
backgroundcontrast effect during slides, which makes them flicker.
As the panel is shown on screen all the time, this is quite a visible
bug. To fix this, when the slide effect is started, we check for window
types and properties of each window, and force the blur flag on if it's
unset.
If the background contrast flag is set to false, we leave the window
alone assuming that there's a reason to force it off. Windows that
are newly added during the slide get the same treatment, so something
popping up while sliding (such as the desktop switch OSD) also gets
the background effect applied.When the effect stops or is interupted, we
unset what we've set, and clean up our internal bookkeeping.
Thanks Martin and Thomas for the thorough review!
REVIEW:115857
57a0667e9d