There is a useful shortcut for the See Also & Classify panel (ctl-cmd-s). When a document is selected, this both opens and closes the panel.
But if no document is selected, then the shortcut is no longer available. Now if the panel is not currently open, this is logical - there is after all no document to be compared or classified. But if the panel is already open - usually because I’ve finished classifying a list of documents - the shortcut still doesn’t work and I have to close the panel with the mouse, which is (mildly) irritating.
I think it would be less disruptive if the shortcut always worked, irrespective of whether a document were selected or not - having it open ‘blank’ is no worse than you get when you’ve run out of documents in your list and is easily corrected by repeating the shortcut if you’ve opened the panel in error.
This is a minor issue, of course, but it’s one of those little ‘niggles’ in the interface that it would be good to see smoothed out.