EffectiveScale vs width and height

[Aanson]

Hi again.

I've got a sort..of..viewport border around my screen which I've made to change colour depending on whether I'm in combat, resting, away, dead, etc.

Is there a way to make a frame 'immune' to changes in scale?

I've tried using, for example:

myFrame:SetWidth(GetScreenWidth() * 0.005);

... instead of using a conventional fixed width, but surprisingly, even that doesn't remain the same size when scale is changed.

EDIT: I know there isn't any OnScaleChanged handler that I can use. If I change the scale and re-submit the above code, all seems okay. Is there any way around this necessity?

Is there a magic formula that I'm unaware of?

Thanks in advance as always,

Aanson