Ticket #4911: menu padding

[egmontkob]

Proposed changes

F9 menu:

• Remove the unused (and not Unicode compatible) first letter feature
• Fix the amount of right padding
• Fix horizontal mouse coordinates

• Resolves: Uneven padding in menus #4911

Checklist

👉 Our coding style can be found here: https://midnight-commander.org/coding-style/ 👈

• I have referenced the issue(s) resolved by this PR (if any)
• I have signed-off my contribution with git commit --amend -s
• Lint and unit tests pass locally with my changes (make indent && make check)
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)

[egmontkob]

Shall I maybe keep the "first letter" feature, just in case we wish to use it one day?

Making it Unicode compatible to show a tick symbol is as easy as changing an unsigned char to gunichar.

[mc-worker]

Shall I maybe keep the "first letter" feature, just in case we wish to use it one day?

Yes, I think this feature should be kept, for example, to show menu item as checked/unchecked.

[egmontkob]

Yes, I think this feature should be kept

Done.