I am using a ReportViewer control to render a LocalReport which works all fine and dandy. I is even wrapped in an UpdatePanel using ASP.NET AJAX to stop the flicker when expanding and collapsing groupings. Still works nicely. Click and drag the web part and move it around to other zones... fine.
Where the trouble comes in is when you just click the titlebar of the web part but then don't drag before releasing the button. For other web parts that don't use the ReportViewer control everything behaves as you expect. But for the web part with the ReportViewer, I get a scripting error stating the "something" is "Not Implemented".
This is with using IE6.
There seems to be a "hidden" <IFRAME> that has event attributes set the refer to a variable called "frames" and it is this that in the debugger confirms that is the culprit for returning the "Not Implemented" error.
If the ReportViewer is set to visible = False the problem goes away unsurprisingly, but then I get no report dislayed 
Help...
Your Humble Savant...
Martin