Turns out there's an undocumented "feature" in the appbar code. You have to ensure that the form you attach the appbar to has a border style of 5 "Sizeable ToolWindow", or else the bar will drop down like my app does. Default border style is, of course, "2 - Sizeable", which causes this bug.

'Course, i'm hiding the border styles from view, so this isn't even visible.

Worth bearing in mind if you're going to use the otherwise excellent appbar code.

Cheers

(If anyone's interested in getting the completed source for my ticker app when it's done, get in touch, the idea doesn't seem to have set the world on fire here )