Not so important at all, but just trying to contribute :

Many objects (links) on the Message-form can be dragged into the url-area;
Once this is done, the link shows full screen (so it's functional too).

However, on turning back (back-button from IE) there is a HTML-error (various can occur) and the button-bar looses the numbers on "New messages created ..." and the other 5 buttons with numbers next to them.
A Refresh makes it allright.

The Treeview buttons (+ and -) can also be dragged, but lead to a blank screen;
Whether it is the intention I don't know, but IMO it's functional to drag a thread incl. its underlaying branche to a "new" screen, and when ready, push Back.

I can imagine this all is too difficult, and then it may be better to disallow the dragging.

Don't need a reply, just FYI.
Regards,