Continuing the discussion from Quick Total Sum:
In my earlier idea I thought it would be nice to be able to select multiple transactions at once to see a running total. On top of this, what could be cool is to apply a category to all of those transactions at the same time.
Having just come back from holiday, my preference is to class all spending while away under the Holiday category, instead of keeping them explicit as to what they were while away. I saw a friend on iOS had a holiday spend feature which would save me doing this, but I’m getting distracted.
Categorising multiple things at once would be neat 
