The Help command does not work on my Linux Mint 21 system, because BROWSER env variable is not set so `sensible-browser` does nothing. At minimum, the Help command should report an error when the return value is non-zero.
However, my system does have a preferred browser set to firefox - I'm not sure if this is part of a (freedesktop.org?) standard. Ideally Geany would use that as the default browser tool. Or is that moving to $BROWSER instead?