How do read DrRacket keybindings (and in general) - racket

Question

I have never been able to understand keybinding syntax well (bc it's hard to google if you don't know the name of a symbol to begin with!).
In DrRacket, I see bindings like "c:g" or "esc;g" .. I have tried hitting those keys in order to no avail. I have tried hitting them simultaneously. Nothing seems to work.
What do they mean? And, in general, how does one go about understanding this syntax?

Answer 1

A generic shortcut:
<modifier-key-1>:<key-1>;<modifier-key-2>:<key-2>;...;<key-n>
means:
press both <modifier-key-1> and <key-1> (that is: start pressing the modifier key, and while it is pressed, press key-1, then release both),
then, immediately, perform the same operation for the remaining combinations of keys,
finally, press <key-n>
Where the standard modifier keys are:
c - the control key modifier
s - the shift key modifier
m - the meta key modifier (not present in many keyboards)
a - the alt key modifier (sometimes already used to insert special characters)
(actually there are other key modifiers in different keyboards).
So, c:x;c:g;s:t means the following combination: Control-X, followed by Control-g, followed by Shift T (this insert Σ, the greek uppercase letter sigma in DrRacket), while c:x;c:g;s means Control-X followed by Control-G followed by the key s (insert the greek letter ς). Finally, the combination m-c-right means press both the modifier keys Meta and Control with the right arrow key.
When the meta modifier key is not present, it is often replace by the ESC (escape) key. Since this is not a key modifier, but a regular key, in this case it must be pressed and released before the next character. In other words, esc:g means: press the ESC key, release it, then immediately press the regular G key. esc-c-right means: press ESC, release it, then press C-→.
Moreover, when the ALT key is already used by the operating system to insert special characters, like in Mac OS X, it can be used as regular modifier key in DrRacket by setting a special preference (in Preferences > Editing > General).
In DrRacket you can find the current keybinding with the menu item: Edit > Keybindings > Show Active Keybindings, and you can find the relevant documentation here.