I can add a lot of usability bugs from my list. The most irritable (though not a bug) is that cannot upgrade python to latest version due to kde-guidance package limitation. This holds a lot of software from being installed/upgraded or requires efforts for keeping several snapshots of system. The important bugs that are on my mind:
kpowersave segfaults (no battery indicator); gwenview segfaults; rudimental kbluetooth (no real world functionality); network-manager-kde frontend does not support latest network-manager API
There are lots of bugs and minor flaws that I keep recorded and intend to fix like:
stupid message dialog popups in iteration loops; wrong Shift selection in Konqueror, etc.; a lot of kmail bugs including hangs, UI freezes, network and protocol incompleteness; kpowersave incompatibility with TuxOnIce; kdevelop UI incompleteness, etc.; incomplete handling of keyboard/mouse settings which are not restored on eject/insert; and many, many more!
Have these bugs/concerns been filed?
I am not trying to sound tripe or pompous! I follow the bug tracker but I never heard of some of these issues. Some of them sound irritating indeed.
Darrell