The issue is caused by Qt's weired geometry in X11. Though we set position (0, 0), Qt will place it to somewhere like (0, -640) or (-640, 0), depending on your screen layouts. The fix is ugly but it works: detect position, if it is negtive, set it to 0.
{F7370607}
Fix bug https://bugs.kde.org/show_bug.cgi?id=385885