DTVPro:

Because Strobe is a transition it's going to affect the whole clip. I can currently think of two ways to do this. You can make a project of the full screen clip with the transition, save it and then added it to a track and add the PIP to the subproject. You could also achieve the same effect as the transition using keyframed effects. I'd think the first methods would be quicker.

 

DTVPro:

Because Strobe is a transition it's going to affect the whole clip. 

  Hi DTVPro!    That is what I thought at first.  But after a lot of practicing with it, I can report that it depends on the transition.  The simple fade and dissolve transitions definitely do NOT affect the entire 1920x1080 frame, just the individual Picture-in-Picture clip (track) that they have been applied to (which is what I want to happen).  And the same is true for some of the other transitions, like "Sun Wipe", "Bubbles" and "Falling Crystals", as well.    All of those transitions affect only the individual PiP clip (track), not the entire 1920x1080 frame.   Which, again, is what I would want to happen.

I guess it really is just transition specific, and however that particular transition was programmed.   Starting with 9 tracks, with a PiP clip on each of them, The "Strobe" transition affects whatever track it has been applied to, and then all other tracks BELOW it.   So even "Strobe" isn't even affecting the entire 1920x1080 frame, just any tracks below it on the timeline.   (When I wrote the OP I had only tested it on the top-most track, which is why at that time I assumed it affected the entire frame.)

 Oh well.  I guess it just comes down to experimenting and observing if the transition can do what you want, or not.  Each transition could behave different from others.

 Thanks for those work-around ideas, that is exactly what I will go to if I really have my heart set on a transition that doesn't play inside a PiP box.... !