This leads to a visual glitch as the centre box size changes, but only the part that cover the window gets properly updated leading to a broken box. See the attached screen shot to see an example.
Created attachment 75793 [details] Demo of the effect
http://git.reviewboard.kde.org/r/108005/
Git commit 16c69a13f8c35a67ae5c8907f2f377fa72297bec by Thomas Lübking. Committed on 29/12/2012 at 16:27. Pushed by luebking into branch 'KDE/4.10'. snaphelper: repaint center rect on resizing client FIXED-IN: 4.10 REVIEW: 108005 M +14 -2 kwin/effects/snaphelper/snaphelper.cpp M +1 -0 kwin/effects/snaphelper/snaphelper.h http://commits.kde.org/kde-workspace/16c69a13f8c35a67ae5c8907f2f377fa72297bec
Git commit d388e3ff1cbe2d940974eab075d11015757349c8 by Thomas Lübking. Committed on 29/12/2012 at 16:27. Pushed by luebking into branch 'master'. snaphelper: repaint center rect on resizing client FIXED-IN: 4.10 REVIEW: 108005 M +14 -2 kwin/effects/snaphelper/snaphelper.cpp M +1 -0 kwin/effects/snaphelper/snaphelper.h http://commits.kde.org/kde-workspace/d388e3ff1cbe2d940974eab075d11015757349c8