I would love the ability to have an "Ignore whitespace" toggle on the popup side-by-side diff viewer.
Nowadays, we utilize the side-by-side diff to more clearly see what changed in a changeset or pull request. We love it. Great stuff. But sometimes we get a contribution from a boneheaded developer who decided to use his IDE's "format" functionality to format the code according to his personal preference, and this can make it very difficult for us to spot the actual changes in the file, as opposed to just whitespace changes.
Yes, the side-by-side diff viewer popup thingy does enable us to better see the whitespace changes than the standard diff output, but adding an Ignore Whitespace toggle would be absolutely wonderful.