The problem with submenus opening in wrong position under Wayland was supposedly fixed in qt 5.9.2, but this problem is still happening with submenus from dolphin context menu, mainly with "open with". I use Arch Linux, dolphin 17.12 rc, qt 5.10.
Just Dolphin, or throughout Qt/KDE apps?
I noticed this problem only with dolphin so far. It does not occur always.
Just happened again on neon dev unstable. "Create New...", "Activities" and "Compress..." submenus appeared in wrong position.
My system is affected. When there is not enough space on either side of popup then it should show itself on a sensible place, insteads it covers previous menu. Tested with dolphin and kate. Other problem may be related, systemsettings left sidebar mouseover tooltips are misplaced. They should be rendered near cursor, instead they show in top left corner of a window. Plasma 5.12.5 Qt 5.10.1 Frameworks 5.45 Arch
Possible duplicate: https://bugs.kde.org/show_bug.cgi?id=391172
Bug 391649 is about tooltips in system settings.
*** This bug has been marked as a duplicate of bug 395177 ***