I have 4 monitors (2 on top of 2) and maximizing a window on monitors 1 and 2 works as expected (maximized window doesn't get partially hidden behind the Plasma panel). Anyways, maximizing a window on monitors 3 and 4 (the ones that are on top of the other 2 monitors) is broken. Windows will take the entire monitor height instead of having a height = (monitor height) - (plasma panel height). On monitors 3 and 4 there weren't any panels by default, so I added 1 empty panel to each and set the option "Always visible". I'm not sure if this is a kwin or a Plasma bug, retag if necessary. Reproducible: Always
Neither. Inner panels cannot strut :-( *** This bug has been marked as a duplicate of bug 299247 ***