Attached is a test case. If I enable the 'Zoomable()' I can see the statusbar. It seems to have something to do with the Icon. If there is no Icon then I can see the statusbar even with no 'Zoomable()', but the application extents itself over the taskbar at the bottom, which is not the case when Icon is used.
Without Zoomable() functionality in Maximize() mode window has the status bar, but hidden behind Windows task bar (always "one row" bellow top line of the task bar). Some bug with getting a height of available area?