Add possibility to select all items from all pages

In the intranet i wanted to download a whole selection (9 pages for 170 photos). I had to click the checkbox in head column on each of the 9 pages, then to click export. I think it should do as in Gmail web interface. Click the main checkbox for page 1 (checks all documents of page 1) then a box appears under the head column line saying "to you want to select all 170 documents of this selection?", Click to do so and then export. Otherwise it can be very long.