@Logi: did System Settings/Display also start working i.e. allow placement of monitors? Or is it (and krandrtray) just not breaking your settings? If it is all now working as expected then it suggests some library that needs to be installed that KDE does not have/is not installing, or setting that post-install of grandr makes that KDE install does not. If Display and krandrtray is still not working it suggests a bug that could be fixed by comparing grandr with krandr.

Would also be useful if you posted on the bug https://bugs.kde.org/show_bug.cgi?id=201866 or whatever its equivalent is. Although note it is assigned to someone I believe has other priorities at the moment (assuming it is the same boiko working on migrating k3b>>kde4). Maybe someone else could take a look...

@putt1ck
I agree with you this is a very important bug. They should fix this asap.
Everybody that uses intel / radeon / radeonhd driver cant setup dualhead with the display settings tool. So for a leek it will be hard/impossible to get dualscreen working. I got same problem and fixed it by editing xorg.conf; for a leek this isn't an option...

I believe llunak has a functional version in one of his branches.