Alt+tab is great to switch between windows, and alt+` is handy to cycle between the windows of a given application, but it's hard to use these key shortcuts together to find an app (alt+tab) then drill down (alt+`) into the windows of this app. This behaviour is desirable because the tabbox window order is not ordered by application, so it's quicker to get into related windows this way. I'm not sure why (key grab?), but it's only possible if you release alt. Apparently gnome shell does work let you work like this though.
It's not possible (atm) because the feature is invoked by kglobalaccel which does indeed no longer receive the shortcuts. KWin has to manage that inside the tabbox (noticing that the other shortcut was triggered and switch mode on that)
*** Bug 322176 has been marked as a duplicate of this bug. ***
Git commit cb1005120a6aaef4d3e894cb66315112354cf9cd by Thomas Lübking. Committed on 29/09/2015 at 21:02. Pushed by luebking into branch 'master'. support changing tabbox mode Allow to change from general window cruising to application specific cruising w/ releasing the Alt key FIXED-IN: 5.5 REVIEW: 125392 M +79 -116 tabbox/tabbox.cpp M +1 -1 tabbox/tabbox.h http://commits.kde.org/kwin/cb1005120a6aaef4d3e894cb66315112354cf9cd