Assume you add "Edit with Vim" command to the context menu of
.txt file. This extension is usually associated with
txtfile key. The commands are listed in the
shell subkey. The default value of the command key is the name of the command displayed in the context menu. If you add
& before any of the characters, then the following character becomes the keyboard accelerator.
Let me explain using an example.
(Default) = txtfile
(Default) = Edit with Vim
In this case, the command Edit with Vim would not have an accelerator key. Change the value to
Edit with &Vim, and then
V would be underlined and pressing it will invoke the command.
If your editor uses a context menu handler to add the item to the context menu, then the only way to change the accelerator key is to edit the string resources in its executable file.
I didn't answer the original question though.
The default Edit command for text files comes from the following registry keys:
(Default) = (value not set)
The shell make the first letter the accelerator. To change it, assign the value to
(Default) = E&dit
The accelerator for Edit command has changed to