Suggestion: Filters should apply to all info & tools

I have my cards stored all over right now, so I'm looking to purchase card boxes to store them by set. I went into my inventory thinking I would filter by set and it would show me to how many cards that filter applied, but nope, the total number at the top remains the same despite the inventory.  I figured I would try to export as a CSV, then, and use a function to count that column up - but, alas, the export takes my whole inventory and not what I was seeing at the time.

This is counter-intuitive in my opinion - all of the headers and tools ought to only apply to the cards that the user has filtered for. Alternately, I'd like to be able to switch this option on - for some reason I feel like the total number up top USED to change with the filter, and no longer does, but I'm not completely sure.

Or at least add some way to count up all the cards that are returned from a filter! Thanks.