Yet another question on the toolbar...

I've added image lists for the active buttons, and for disabled buttons. I have a separate routine that enables/disables menu-items and toolbar buttons depending on availablilty of data.

It runs at app startup, after which a number of the buttons are disabled. Then when load a file, it is run again, to enable the applicable buttons. So far, so good. However, after the routine is run, the toolbar is not repainted until the mouse moves over it. Even the explicit instruction to Refresh doesn't change that behavior.

Is there a setting / instruction that I'm overlooking?