Theory:
----------
because PresentWindowsEffect::screenCountChanged() is shortcut
for "if (!isActive())", but the desktopgrid doesn't call
PresentWindowsEffect::setActive (or at least
PresentWindowsEffect::screenCountChanged), so the effect can
"miss" the increasing screen count change (it sees the signal,
but ignores it) and when desktopgrid calls it, it assumes the
m_gridSizes array is big enough (but it isn't)
Steps:
----------
1. effects are loaded, 1 screen present
2. 2nd screen gets added, but inactive effects ignore that
3. desktop grid gets activated, updates according to screen count,
calls presentwindows for screen #2
4. presentwindows data is only prepared for one screen from step 1
=> BOOM
BUG: 351724
CCBUG: 326032
FIXED-IN: 5.4.2
REVIEW: 124960
classes. Example code has been added to present windows and desktop
grid, if this code is not to be used by KDE 4.3 it should be removed and
added to a test effect instead.
svn path=/trunk/KDE/kdebase/workspace/; revision=922039
