I think that could be useful to have possibility of using Quick Info also on Info Windows. Usera sometimes has to see informations based on selected rows (not only number of selected rows), for example in Generate Invoices (there is a ticket to migrate Generate Invoices from special form into info window) could be useful to see Total Price for all selected rows. Currently are on Info Window displayed only contextual helps for Info Window parameters.
I think that there could be supported few basic operators (there is no needed), but it can be probably achieved easily by SQL statement in Status Line.
Some basic operators to support: