IE: Drag and drop of component items is sometimes failing in template composer

The rest service requests are sometimes not fired. Further more are for a move operation two rest calls done to update the source and destination container, this is triggering each a refresh of the iframe, which I think could result into problems. Note also the pageModelStore gets reloaded twice. However this seems to be a pure timing issue, which is probably related to the slow javascript engine of IE in my case.

A solution could be to do the data update chunked or rework also the rest backend service to accept all changes in once. The muted ajax request are probably related to not being able to call two ajax request from the same call stack.