How to repeat:
* open inventory, hover with mouse over some item
* push and hold LMB
* push and hold RMB
* release first LMB then RMB
(that's actually not so hard to achieve accidentally on a notebook touchpad)
The result is that you drag the item, but at the some time item-info window opens. But mouse clicks go *under* that window (i.e. in PST, you can actually swap dragged items by blindly clicking the window at right places). Surprisingly, it's sometimes possible to close the identify window by clicking on *some* parts of the Close button (e.g. left 1/4). If not, Escape closes the window.