Set a keyboard shortcut for expanding/collapsing a channel in the sidebar list

[ggonzales]

In the Sidebar-style interface, the channel list is shown on the left. The user has to click on the expand/collapse icon in order to show or hide the list of users of that channel. There should be a keyboard equivalent for this, as in for example, Vienna, Command-left and Command-right cause a group folder to collapse/expand respectively (the collapse can also be done with the left arrow key only).

[grahamperrin]

I'd like the accelerators to be:

* command-right to disclose
* command-left to disclose

In the meantime, for both disclose and close I type
/names

(It took me a long time to realise that /names worked for close as well as disclose.)