Windows desktop: Double-clicking .4ui file opens new app, not new tab

It's nice to have multiple tabs for keeping plots open in ForeUI, so I was surprised to find that double-clicking filename.4ui in a desktop folder doesn't open it in a new tab, but opens an entire new ForeUI session -- you wind up with two (or more) instances of the entire application.

For some reason this doesn't happen under Mac OS X (just checked). Can you have the Windows build behave the same way, and make .4ui files opened from the desktop load as multiple tabs in a single application session?