Re-draw last frame in editor window

Hi all

Just wondering if there is a nice way to redraw the last update of an editor window, I only want the ui to update when the editor window is focused, but still want it to show the last values when its unfocused.

Any idea how i would achieve this (I not really in a position to cache the last values and then draw a different ui from the cached value if not focused, although i feel like this is going to be how i have to do it)

Thanks