So far KWin simply does not render a thumbnail if it would be only partially visible in the tabbox. This will be fixed in 4.9. Reproducible: Always
Git commit 774946bdeda616167ac249f6c4b3550c48f813ea by Philipp Knechtges. Committed on 24/03/2012 at 14:51. Pushed by knechtges into branch 'master'. kwin: provide clipping for the TabBox thumbnails REVIEW: 104399 M +13 -7 kwin/scene.cpp M +1 -0 kwin/tabbox/qml/clients/present_windows/contents/ui/main.qml http://commits.kde.org/kde-workspace/774946bdeda616167ac249f6c4b3550c48f813ea