Current problem
It is impossible to hide a channel without using the "Hide muted channels" setting. This means that you can't have hidden channels and muted channels. This causes a problem for me because I will often mute a channel (or category) because I don't want the unread indicator but still want to be able to view it.
Proposed change
Add an option in the context menu to hide a channel. It could then be moved to a seperate "Hidden Channels" area where you can add it back. Accessing Hidden Channels could be done via a button near where the current Members button is. This would also allow hiding link channels, which there is currently no way to do.