{dim} tag gives actual dimmed/bright state, dimmed = 1, bright = 0
(Alt. {bri}, bright state, bright = 1, dimmed = 0)
eg.
Opacity 100 - 75*{dim} --- 75% transparency when dimmed, 0% when bright
Width 535 - ({dim}*200) --- Smaller when dimmed
[edit] I tink maybe {abright} is what I was looking for...