[Sampler] Drag from desktop applications -- fails with dir on Firefox

Testing the
Drag from desktop applications
sample.
In Firefox 7, on Windows XP.
If I drag a file from Windows Explorer, it works fine, showing the name of the file.
If I drag a (small) folder, I get an infinite (or verrrry long) spinning wheel.
When I refreshed the page, I got an internal error message, and clicking on the restart link didn’t work. I had to clear jsession cookies to get back to normal sampler display. Although I cannot reproduce this error message.
If I navigate away to another sample, it works fine, and when I go back there, the spinning wheel is still here. Stops if I drag a file or if I hit Reset.

Same test with Chrome 14 just shown the name of the folder.

I suppose I should open a bug, but I prefer to get opinion on this before.