Library showkey.el (code) gives you what you request, I think.
It defines two global minor modes, which give you two ways to show keys you type:
showkey-tooltip-mode – Show only the last key used, in a tooltip. This is refreshed with each such event. By default, it uses large red characters, just as you request.
showkey-log-mode – Show a log of such events,...
I have just found this from its Github page.
Not one key but, If you press also for C-h u you can go for previous state.
which-key-undo can be used to undo the last key press when in the middle of a key sequence.
You have a couple of options. You can use the windmove-delete-up, -down, -left and -right functions. I use them with these bindings:
(global-set-key (kbd "C-c W") #'windmove-delete-up)
(global-set-key (kbd "C-c S") #'windmove-delete-down)
(global-set-key (kbd "C-c A") #'windmove-delete-left)
(global-set-key (kbd "C-c D"...
Looks like it isn't defined.
Hyper is all on the OS's side - I don't think there's any way to map it natively, but you can stick in KC_MENU or something similar to be redefined in xmodmap or the equivalent for your distro.
http://www.usb.org/developers/hidpage/Hut1_12v2.pdf Page ~58. No
reference to hyper in ...