Abstract:

It would improve ergonomics, if one can set the channels navigation to the top. Think of any bookmarks bar of a browser.

Implementation:

Most likely an hbox of comboboxes for the baseline. As data is a 2level hierarchy, one could use either a combobox of horizontal comboboxes, or labels and horizontal spacers for displaying a server's channels. I think it depends on the channel amound which visualization is better.

Rough mock: https://pastebin.com/yWGdPuke