And here's another thing - that you might already have on your list? - I think could also be done to make XY even better, and bringing the Catalog to the next level : brought the power of UDC to it, in a way.
Instead of Destination, why not add a Command list that would include all UDC's categories (Go To, Open, Rename, etc), and rename Destination to Argument.
Then, the "Open on click" checkbox has to go, and instead those items must be assigned to the "Open" command instead of "Go To".
That way, all the "tricks" on Catalog would still work, Ctrl+Shift+Alt Click to scroll there, or drop/Ctrl+Shift Click to open with, but not only could one start an open with operation on one single, simple click, but one could also start move/backup/rename/etc operation using one click as well !
Being more of a mouse guy I'd like that, a lot, as it'd be better/easier/quicker than using the menu interface. Of course, the best would be to also have another possibility, the custom TB buttons
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