PuTTY wish modified-fkeys

summary: Unique codes for modified function/special keys
class: wish: This is a request for an enhancement.
difficulty: taxing: Needs external things we don't have (standards, users etc)
priority: low: We aren't sure whether to fix this or not.

We occasionally get requests to provide unique escape sequences for function keys (and other special keys) with more combinations of modifiers than we currently support (e.g., Fn, Shift+Fn, Ctrl+Fn and Ctrl+Shift+Fn).

Sometimes it's even suggested what sequences these should send. (`xterm-keyboard' has some suggestions, but also claims not to be trustworthy.)