Currently keybinds can only be set to single keys, without modifiers, and certain keys cannot be used at all. E.g. binding "jump" to "Enter/Return" looks like it binds just fine in the menu, but doesn't actually perform the jump when pressed.

Imagine that instead of using keys 0-9 for the toolbar you used keys 1-5, and held shift to access the last 5 slots instead. No longer do you need to reach over the entire keyboard to reach the last slot. In this sense, any combination of ctrl, alt or shift + key should be allowed for key binds, including multiple modifiers at once. E.g. ctrl + shift + 1 should also be possible.