I am using iTerm2 under High Sierra 10.13.6. iTerm2 lets me assign Control-Command key combos to particular actions. This mostly works fine, but at least two of these do nothing: Control-Command-B and Control-Command-D. I suspect they are being grabbed by something at the system level. However, manually walking through all of System Preferences -> Keyboard -> Shortcuts didn't show anything for these two.
Is there a way to get a list of all key combinations and map them to what they are (or are not) assigned to?