Yes. I can confirm this.
It's been bugging me since 6.3 as well, but I never thought enough of it to post a bug report. To *me*, this is not what I'd expect mIRC to do. My OCD always ends up having me click the channel in the switchbar to remove the highlight state even though the window is still active-- it can get annoying sometimes.
To clarify though, another window doesn't have to open by itself, you just need to have another application window other than mIRC active. Then, if the highlight state for the active switchbar item changes during that time, it will remain that way when mIRC is reactivated.
