iMac when used with bluetooth Apple keyboards and mouse has a faintly annoying problem of the inability to use the mouse if it doesn’t automatically gets connected to the system. A possible remedy and workaround for this is to use keyboard keys for mouse control.

  • Press F8 (or F7 in the Macbook) key on the keyboard to enable switching the command palettes in the settings window.
  • Use the Tab to scroll up and down in the command palette.
  • Use the Space bar to make the selection click at the desired command.

Some refs for this problem are: