Office.context.ui.displayDialogAsync gives us the ability to open a dialog of a certain size, but the size options are only in percents of the parents window.

This could be fine if we could know the size of the parent window from an add-in - we could get it and do some calculations, but CORS blocks us from that.

Using only percentages puts us in awkward situations where we have a dialog with a decent amount of content that we need to make responsive to a tiny window when there is still a lot of real estate available in the parent.