I'm using foobar2000 1.1.6 and Columns UI 0.3.8.6.
Is there a way (e.g. using variables) to display AlbumArt for the currently playing track in foobar2000's notification balloon?
EDIT: I'm sorry. I've missed reading 'columnsUI' in your question. My answer is providing another solution. I will leave it anyway, maybe it will help someone else.
Reference: Notification: A nice popup in the corner
As I mention in a comment upper, foo_popupplus has the undesirable effect of crashing my foobar2000, which is not a tolerable behaviour. As a consequence, i investiguated a little further and found out foobar-gntp. Already using Growl for Windows, it made sense for me to use a centralized notification system, even if it is not the classical notification baloon of Windows.
Unfortunatly, it is not a direct solution to my initial issue.