The Glance Expansion Shortcut

[renlei81]

I used to use Arc and I appreciate the Glance function very much. And I was impressed the same function in Zen. However in Arc there is a shortcut like ctrl + O, which could expand the glance window. However I have not found a similar shortcut to expand the glance in Zen, neither in settings nor in about:config. So I expect that there could be a shortcut for more convenient expanding of the glance.

[KyleKincer]

dupe of #5079

[renlei81]

Thanks a lot!