Re-Arrange controls in CControlbar, when?

Hello,

I have to rearrange my controls in a controlbar based on the new size resulting from dock/undocking of the bars or resizing of the mainframe.

Is there a message I can use?
How to determine the new height when docked?

I tried to use its OnSize-function. The problem with it is to get the new height. When the function is called, the height I get from GetWindowRect is the old height.

Is there a better function than OnSize() ?

thx.
Ralf