I generally set 'units' property as 'normalized' for all figures and uicontrol elements in my codes.
Even the screen resolution changes from one monitor to another the position of your figure window appears in the same position.
get(gcf,'Position') equals to getpixelposition(gcf).
If you use OuterPosition you will get different value.
Position and OuterPosition are different things. Check below to see Position, InnerPosition & OuterPosition.
Also check below link Jan has written: