I know it's been mentioned before but let me just mention it again because of how BADLY it needs to be fixed:

The left panels, in full screen mode, DO NOT turn on and off properly after switching out of full-screen mode and back in, and there are generally just an endless number of bugs associated with the logic for turning on and off the left panels. They randomly shrink down to nothing and you have to expand them again, turning them all off sometimes turns them all back on, etc.