How do I close the Intelliprompt list when the editor loses focus

I am seeing a problem where a user uses a shortcut key to move to a different window (sometimes another SyntaxEditor window) while the iltelliprompt list is dropped down.

I expected the list to close but it does not.
This is espesially confusing if the new window is displayed on top of the old one. (The intellisense list appears in the new window)

I found the IntelliPrompt.MemberList.HideOnParentFormDeactivate property and set it to true, but that made no difference.
(I would expect it to have a default of True anyway - docs don't say what the default is.)

If that's not what this property is for then how do I make the list close when the editor loses focus?

I added a LostFocus handler which checks to see if the list is visible and calls Abort() if it is, but that is not optimal.

Thanks
Mike