Screen shot attached.   There is a serious bug somewhere deep in sonar that surfaces after a heavy work session.  
 

Unfortunately the screen shot is too small to show what issue you are having.  Could you also describe in words what issue you are having.

Steps to reproduce please (yup image too small and I'm not sure what we are supposed to be looking at).

An attempted paste gives a blank dialog box, the screen stops refreshing.   Until I turned off autosave, this kind of thing also resulted in a crash ... now the signal is the screen refresh issue, so I close and reboot and start over, at least not losing work.

Exactly what are you copying and pasting?
Where are you copy and pasting?
What dialogue is it?
What else are you doing?
 
You need to get into the specifics with as much detail as possible so we don't have to waste time asking questions.
We need steps!
 
For those interested larger image here.

Ta.

I'm sorry, this is not an easily reproduced situation: it only happens after several hours of heavy work.  The post was just a reminder to the programmers that there really is or are deep issues that remain.     
 
Also, this arose from many many edits but no weird things like messing with VSTs or FX chains. 
 

I totally get you... I have a few issues I can't pinpoint.
Sadly though without the specifics or even a general background almost impossible to do anything about it. The only way is to test until you get the right conditions to repro.

williamcopper
I'm sorry, this is not an easily reproduced situation: it only happens after several hours of heavy work.  The post was just a reminder to the programmers that there really is or are deep issues that remain.     
 
Also, this arose from many many edits but no weird things like messing with VSTs or FX chains. 
 

Sadly in this format, programmers are hardly likely to even see the comments you've made.

I would highly recommend you reporting this with the emphasis on it being time related issue. I have noticed some oddities with the paste function when I have spent time MIDI editing. i.e. miss pasting even when using the option to paste special or the keyboard short-cut ctrl-alt-V, telling where to paste to have it paste starting on a different track.

williamcopper
I'm sorry, this is not an easily reproduced situation: it only happens after several hours of heavy work.

Given you've apparently seen it more than once but it's never been reported by anyone else (to my knowledge), if it's not environment-specific, I would suspect it's a product of a very particular workflow that you have, and only you will be able to determine the sequence of events that causes it. It seems likely to me that using floated windows might be a contributing factor.
 
Related to that, what are all those minimized windows at the bottom of your desktop?