In the Day view, if I filter by an application (double-click in the lower-right window).
Then in the lower-left window I clear all the issues by assigning them to tags, I want the filter to clear automatically and go back to the full application view again. You could make this an option if someone didn't want it to happen.
I must waste several minutes per day either going down to the filter box and clearing, or clicking to another timeline and back again to clear it. I can't see any reason why I'd want the filter to remain especially if I was just actively clearing the items filtered. It would only auto-clear in that instance.