http://wiki.flightgear.org/CompositeViewer_Support
I've been able to get the whole thing to crash fairly reliably (using latest next), even without loading any terrain/aircraft (and disabling all draw masks to render nothing except for the skydome): simply by tinkering with different OSG threading modes while circling above the sea (ufo) with multiple cloned views (all views inheriting the same draw mask settings, i.e. rendering just the skydome).
The most reliable way to crash is using --prop:/sim/rendering/multithreading-mode=CullThreadPerCameraDrawThreadPerContext
According to the wiki, this is known to be somewhat fragile apparently (Torsten reported this repeatedly) - so this might not even be a CV specific regression: http://wiki.flightgear.org/Howto:Activa ... PU_support
However, compared to Automatic/SingleThreaded, the CV mode crashes rather quickly (under 5 minutes)
Which is a pity, because when using aggressive OSG threading, performance is REMARKABLY GOOD !! (seeing 120+ fps in all 3 windows)
There also seems to be a minor issue inside the main window after cloning, i.e. in that the menubar, OSG stats and any tooltips are shown with an offset in the lower part of the window rather than at the top and PUI dialogs are rendered incompletely - which is "fixed" by resizing the window manually.