Proposed fix for #1408 Window Size in windowed and full screen modes.

Proposed fix for #1408 Window Size in windowed and full screen modes.

Tried saving QWidget::normalGeometry, but this was not the correct approach, instead now convert widget to normal size, save data, then revert back if minimised or maximised
This is just preference, but I probably would have used `ismax` and `ismin` or `is_max` and `is_min` since the word `mined` reads wrong.