Dedicated keybinds for popups - "popup mode"

[wnhrt]

Using Ctrl-d/u and Alt-p/n isn't very intuitive.

My proposal is to "focus" popups and allow dedicated keybinds while they are open. Like a "popup mode".
For example, when a popup is open, users could press j/k to scroll and h/l to switch signature-help. Pressing escape would close the popup and return to normal keybinds.

If there is already a discussion or issue about this topic, please let me know, I couldn't find one.