FR: Add a "Cancel query" button to the toolbar

[thefreakquency]

In some cases, you might end-up having a long-running query:

If you realized you made a mistake and would like to cancel it, there are no options to do so. It will indicates "running" in the status bar until it timeout.

Having a way to cancel the query, either using a toolbar button, menu item (under Query) or a keyboard shortcut would be a time saver.