Bug 364703

When dragging clips in from the project bin before the proxy has been created, the clip on the timeline does not appear to display the proxy clip once the proxy clip does complete. 



Reproducible: Always

Steps to Reproduce:
1.load new project, with some footage that takes a long time to get a proxy for
2.drag a clip in from the project bin
3.wait for the proxy to complete
4.Drag cursor around the Clip Monitor, then around the project monitor. 


Actual Results:  
Dragging the cursor around the project is a lot slower until the clip that was dragged out earlier is deleted from the timeline and dragged out again.

Expected Results:  
The proxy to benefit all clips that refer to the base clip has been generated, and is enabled for that clip. If it is, then the proxy should be played back instead of the source clip. 

Proxies have been troublesome for a long, long time. I remember submitting quite a few reports on proxies working for one thing, and not the other. 

As far as I understand it, there should be no reference to proxies in the timeline itself. Rather, we already have a list of files in the project bin, and know whether or not proxies have been enabled for them. 

For playback, before each clip is played back, there should be just one global check on whether proxies are enabled for the project AND for that clip AND the proxy exists. 

If yes, then feed the proxy instead of the original footage to melt. If no, use the original footage?