I use many shortcuts for my work in vim. Other shortcuts are taken by plugins.
Sometimes I would like to add a shortcut for a new command but note afterwards that the shortcut was already taken.
Is there a way to see a list of all available shortcuts in VIM? (all ctrl-shift-alt shortcuts)
Type :help index
to see the mappings (shortcuts as you name them) and commands defined by vim itself.
Type :map
to see the mappings defined by your vimrc and plugins. Type :verbose map
to know where each mapping was defined.
Also :help map-listing
to check what's displayed, but you probably already know about it (it's in map.txt help manual).