Collapse Unchanged Fragments

Hi,

I'm getting a lot of use out of the 'Collapse Unchanged Fragments' button in the Diff viewer....

... so I usually try to setup keyboard shortcuts for the features I like best and use the most often.

I tried searching for 'collapse unchanged fragments' in the Keymap area of settings, but couldn't find anything.

Could you let me know what I should select, to assign it a key?

Thanks,

Tim