Support system's prefered pixel sizes for icon

[Lakritzator]

See https://docs.microsoft.com/en-us/windows/win32/api/commctrl/nf-commctrl-loadiconmetric and there specifically the mentioning of SM_CXSMICON & SM_CYICONSPACING etc mentioned here: https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getsystemmetrics