Additional chat-related features and issues within Microsoft Teams for business
One of my smart users realized that if she set her zoom in Teams to 115%, the left pane collapses when you drag the drag any side border to narrow the width of the Teams app enough, and when expanded the left pane reappears.
This worked brilliantly. I was so frustrated how it scrunched up the main chat threads, and I didn't want to enlarge the window at all. Setting it to 115% not only collapsed it, but changed it to it only appearing when the mouse is over. The window is still the same size, and because it shrunk things down when it was stuck, the size increase doesn't actually change from how it used to be!