Actually I found the "Detach" button at the top of the TruClient pane. That moves the pane into its own window and the modal dialog problem does not happen. As long as I run this way, it works well (short of crashing FireFox every once in a while...)
Using VuGen 11.52
And I see that the FF that is launched is version 8.0.1... I assumed it was the same as the version I run from the desktop; did not realize that VuGen bundled it's own.