Make welcome message configurable

[Eliasin]

Hi! Just a small change that closes #49. There are some things that could maybe go back and forth like the .clone() at get_default_message to reduce .clone() at callsites not matching the rest of the config because it returns an owned string but I think the rest should be good.

I was also thinking about a PR that chooses different background images based on aspect ratio/display name (I have a 3:2 laptop screen but plug in a 16:9 monitor that I'd like a different background on), but I know that cage can mirror across two screens and I wouldn't know if that would make the feature impossible. I'm not familiar with relm4 and Wayland development in general so I'm a little fuzzy on what the behaviour would be in that case though I did spot relm4::abstractions::drawing::DrawHandler::size so that gives some hope for the possibility of dynamically detecting aspect ratio.

From what I know to add background based on name would require speaking Wayland (wl_output::name unless relm4 or the gtk bindings abstract it) so that might be a dealbreaker since it'd add a lot of complexity. Let me know what you think about either of these ideas, I recognize it might be out of scope or just plain too much work to maintain.

• Docs Updated
• Pre-commit hooks passing

[rharish101]

Everything looks great, except for one tiny little question in the sample config file that I have noted down.

[rharish101]

Thanks for the PR! As for the backgrounds, that sounds like too much complexity to have different background images on different monitors. I'd recommend rather to choose a large 3:2/16:9 wallpaper and use one of the different background fits.

[Eliasin]

Thanks for the quick reply! (and oops on the config)

And thanks for the insight on the background image.