fix(help panel): prevent duplicated key displays

[TomJGooding]

Fixes #5037

Please review the following checklist.

• Docstrings on all new or modified functions / classes
• Updated documentation
• Updated CHANGELOG.md (where appropriate)

[willmcgugan]

I don't think this will de-duplicate the key displays, except where we have identical keys to the same action.

i.e something like this:

BINDINGS = [
    ("foo", "do_foo"),
    ("foo", "do_foo"),
    ("bar", "do_foo")
]

Should display foo bar for the key display.

[TomJGooding]

Sorry @willmcgugan, I'm not sure I understand what you mean.

Currently if you define a binding with a comma-separated list of keys along with a key_display, the help panel will duplicate that key display for each key as described in the linked issue #5037.

I don't see any issues with duplicated keys with your example bindings above, but perhaps I'm missing something?

[willmcgugan]

Consider the following:

from textual.app import App, ComposeResult

from textual.binding import Binding
from textual.widgets import Footer


class HelpPanelApp(App):
    BINDINGS = [
        Binding("a", "bell", "Ring the bell", key_display="bar"),
        Binding("b,e,l", "bell", "Ring the bell", key_display="foo"),
    ]

    def compose(self) -> ComposeResult:
        yield Footer()


HelpPanelApp().run()

This will only display a single key, when there are multiple that would apply.

A contrived example perhaps, but even more likely now we have keymaps.

[TomJGooding]

Thanks Will for clarifying. I see your point about this edge case, but why would you define multiple bindings like this? The key panel also wouldn't account for these bindings having different descriptions, so why should the key display be different?