Currently it is impossible to move items in channel list with the mouse. Instead, one must know the keyboard shortcut of 'ctl-shift-pgup/down', which is not the most intuitive or discoverable thing in the world. Further, if your hand happens to be on the mouse, sometimes it's nice to be able to mouse things.
To this end, I suggest the addition of two items to the right-click menu on the channel list, "move up" and "move down", which can be used to move an item up or down in the list. (Or maybe just a "move" item with a submenu containing "up" and "down".)