QScreen may return non-zero x0/y0 for geometry in a multi-screen setup, those should be taken in account to center the window properly on active screenDo not force geometry or window hints when opening systemmonitor
This should let it position properly on a multi-monitor setup and reduce interference with user-set KWin preferences
Could be related to bugs about it opening off-screen ( #BUG: 368158 / #
BUG: 356706 )