Improve ability to select/de-select entire sub-tree in the Export Space page

Just found the Export Space page which is really nice. I want to export a specific page and all descendents. My sub-tree to export has a lot of pages, and there are a lot of pages in the wiki as a whole. At the moment I need to de-select everything and then individually select each page to export.

It would be really nice if the checkboxes behaved like a lot of tree views with checkboxes in other apps. That is, de-selecting should de-select all descendents and selecting should select all descendents.