Edit the slice name in-place

[mistercrunch]

The slice name is displayed in the explore view, but the only way to change it is to hit "save as" and do a server round trip.

It'd be nice to be able to edit it in place. To make the feature clear, the mouse icon should switch to cursor: text; and ideally the title is edited in place (as opposed to a popup)

@graceguo-supercat

[mistercrunch]

dup of 2796, closing