With the Tab key you can jump through all relevant control elements in sequence. This is especially useful when editing a card, as it allows you to work through all editable fields from left to right and from top to bottom.
For the following shortcuts on macOS, use the Cmd key instead of Ctrl.
Esc -> Close Card Ctrl + S -> Save Card Ctrl + Shift + S -> Save & Close Card Shift + Esc -> Save & Close Card (alternative) Ctrl + M -> Open New Card of Same Proto Ctrl + P -> Open Associated Proto Ctrl + I -> Show Card Properties Ctrl + H -> Show Mutation History of Card
Ctrl + M -> Create New Card Ctrl + P -> Open Associated Proto Ctrl + I -> Show Card Properties Ctrl + H -> Show Mutation History of Card
Ctrl + B -> Bold Selected Text Ctrl + I -> Italicize Selected Text Ctrl + K -> Make Selected Text Into a Link