Menu item width

[bhh32]

Summary

Refactors MenuItem from an enum to a struct wrapper, adding a .width() builder method that can be applied to any menu item type. This lets applications control submenu widths without hardcoding values into libcosmic forks/patches.

Problem

Currently, there's no way to set a custom width on menu items. This causes issues when menu content (like file paths) is longer than the default width, resulting is bad looking UI.

Before:

After:

Changes

• Renamed MenuItem enum to MenuItemKind
• Created new MenuItem struct wrapping MenuItemKind with optional width field
• Added .width(u16) builder method
• Added convenience constructors: button(), button_disabled(), checkbox(), folder(), and divider()
• Updated menu_items() to apply width to all item types.
• Updated responsive_menu_bar.rs to use new API

Usage

// Old API
menu::Item::Folder(fl!("recent-folders"), items)

// New API
menu::Item::folder(fl!("recent-folders"), items).width(300)

Migration

Existing code using enum variants (Item::Button(...), Item::Folder(...), etc.) should switch to the method constructors (Item::button(...), Item::folder(...), etc.). The From impl provides backwards compatibility for code that builds MenuItemKind directly.

[mmstick]

It would be better if we calculate the width in the widget so that they're automatically resized.

[mmstick]

A min and max width might be better as the widget should be calculating width automatically. The width will change depending on the language use.

[mmstick]

This should also update the menu examples, and have examples included in the code docs

[git-f0x]

Might also be nice if there was a context menu widget that has the same behavior as the menu bar popups, so that it can have nested menus (e.g. Open with... > list of apps in a nested menu in COSMIC Files). Or maybe the same widget and it just differs in the way it's spawned?

[bhh32]

This should also update the menu examples, and have examples included in the code docs

I can definitely update the examples and code docs.

[bhh32]

@mmstick, I've updated the examples and doc comments. I also added min_width and max_width builder options, updated MenuTree, and get_children_layout to ensure that internal auto-resizing occurs and is clamped to the min_width and max_width restrictions.