What determines if a key stroke is waited indefinitely or if it times out?

Question

I have a very customized vim configuration, but I don't think it has anything to do with this, because nothing has changed the key binding system.

When I press g I can leave the window there and make a sandwich and come back and it's still shown in the part of my statusbar that shows pending keystrokes (I forget what that is called).

But when I press \ (<Leader>) it times out and beeps after one second.

When I check maps, I see that neither g nor \ have primary mappings to just that key (which would indeed cause them to trigger their mapping upon timeout or receiving another non-matching key).

So what then is the difference between these two cases? Why doesn't \ leave me more time, or, why does g not time out?

Answer 1

Certain commands such as g, z, f or Ctrl-W expect another key afterwards. Those commands will call plain_vgetch() internally, which is a function that loops and waits until it receives a key (and ignores certain internal key events such as Scrollbar or Ignore events). By setting some additional global variables, it will be made sure, that those keys won't be mapped and the plain keycode will be returned. But depending on the command, the languange maps might apply.

What will be done, depends on the flags for the normal mode commands (see the definition of the nv_cmd struct in normal.c). The NV_NCH* flags mean that another char needs to be obtained.