Craig, Thanks for jumping in. Although the video has some artifacts at the start, later in the vid when I move the clip, the capture is totally accurate. The changes to the clips persists when scrolling or zooming. My video system is relatively old. It is running the latest drivers, but updates have not been released recently. In general I don't have any problems with video and display issues in Sonar. Is there any sort of video "stress test" that can exercise the functions used by Sonar?
 
FastBikerBoy, I think you hit on the right answer.  I did have "Slide Over Old to Make Room" set.  I changed to "replace old with new", and that stops the strange effects on the other clips.
 
That still leaves me with questions, though. Can anyone explain what the "Slide Over Old to Make Room" option is supposed to be doing when I drag one clip? 
If the other clips moved over by 1 measure when I moved the first clip by 1 measure, that could make sense. Or if the clips to the right of the clip being moved were directly adjacent (no gap), and only then would the later clips slide over as needed to make room (as implied by the name of the option). That would be useful.
 
But duplicating clips and changing lengths of other clips?  That seems very non-intuitive and weird.  Is there meaning in that behavior? FastBikerBoy or scook, when you turn on "Slide Over Old to Make Room", do you also see duplication of other clips on the track? I thought it might be some interaction with take lanes, but I have them turned off.
 
 
 
 

The "Slide Over Old to Make Room" is a mess. It creates lots of clips on separate track lanes. I did not change from comping mode to further research the problem. Never saw the behavior before because I have not used "Slide Over Old to Make Room" before. It has all the makings of a bug to me.

I uploaded another video showing the problem, (zooming in and panning to show the duplicated clips are really there, and not just a video artifact.
www.synthify.com/39477281/684268427/Sonar/SonarMoveClip2.avi
 
The next clip shows that the problem is fixed by selecting "replace old with new".
 www.synthify.com/39477281/684268427/Sonar/SonarMoveClip3.avi
 
 
 

I rarely use "Slide over to make room" but I have in the past in previous versions, without this issue. As I understand it what is supposed to happen is clips are rippled down stream to make way for the clip, either maintaining the exact current gap or aligning to measures if the gap is different.
 
I am almost certain you have discovered a bug. It seems that scook and myself can duplicate it. Report bugs HERE

Checking back in to see if this has been resolved with Platinum, or if not yet, when? As scook notes above the ""Slide Over Old to Make Room" function seems to be quite broken.
 
In the "Readme.rtf", there is a section titled "Drag and Drop Dialogue Options and Nudge Settings", which is quite similar to this issue I reported last year with clips.