Mapping cursor coordinate between QMainWindow and Screen
I've met a problem while mapping cursor coordinates between QMainWindow and Screen.
When I maximized the window and move the cursor to the upper border of current window, I got the global cursor coordinate: (x, 0). After I called the QWidget::MapFromGlobal(), I got the local cursor coordinate: (x, 16). I suppose the y coordinate should also be "0"!
When the window is not maximized, I move the window so that the upper border align with upper screen, and could get the mapped coordinate I supposed. That is, the mapped local cursor coordinate is: (x, 0).
Could any one tell me why the cursor coordinate mapping mechanism is different while the window is maximized and normal. Thanks in advance!
No one can tell me reason? Or, if the problem is confusing, I can re-explain it.