Popup Window doesn’t fits image

[henkjans]

maybe I didn't explane to well last time but I'm facing next problem:

is it possible to change the Popup Window style so that ratio length / width of the popup window is set to the contents ratio length / width?
It seems that this works for text as contents, but what if I only want to popup an image?
Left to the image there is a unused white area. It should be nice that the image fitted the popup window.
Is there a style??