You've never hovered over the chat area? Nonetheless, the bar could could probably use a hint when also hovering the labels area. I'm still unsure how you have written off the designers as simply inept. I could take down any UI with such an attitude.

Excuse my language. But are you fucking kidding me ?

That is the worst UX I've seen in a long time. Since when is blank space considered a target area to hover your mouse over.

Wince every OS (MacOS and Ubuntu and Google anyway) adopted on-mouseover scrollbars and click corner to resize?

You might be also interested to learn about this new peripheral that you put on your desk and wiggle, and--get this-- it makes a pointer on your screen move. Crazy, right? It will never catch on! Touch your desk to interact with the screen? What brain-dead idea will they come up with next?

I get a scrollbar in that pane when it's too small to display all the labels. That makes it pretty obvious, it's strange that you don't have one.

You have never thought to click the edge of a box to drag its border to enlarge the box?