Channel menus open when you click the channel dots, fixes #1960

STT: 
* add a brick
* make sure it has a listener or broadcast line
* click the channel dot icon on the line

Before: empty, bleak sadness
After: the channel menu opens with the color options for the associated listener/broadcast metho


same here, if we assign a class then the style for the nested .color-ui can simply rely on cascading and we don't need to touch `.style` at all