Allow TreeItem.label to support MarkdownString

[TylerLeonhardt]

Looking at the API for TreeItemLabel it seems a bit limited. I'm trying to avoid moving to a webview view and what I need is some way to have certain nodes in a tree view be crossed out. It'd be nice if TreeItem.label could be extended to support MarkdownString.

Proposal:

export class TreeItem {
		/**
		 * A human-readable string describing this item. When `falsy`, it is derived from [resourceUri](#TreeItem.resourceUri).
		 */
		label?: string | TreeItemLabel | MarkdownString;
}

[alexr00]

I am not adverse to to this proposal. @TylerLeonhardt would you be interested in bringing the proposal to the API sync?

[connor4312]

I wonder if we should support MarkdownString (with a subset of functionality) instead of introducing new semantics for text styles.

[TylerLeonhardt]

Interesting... So every TreeItem can only be rendered on 1 line, however, multiple lines is technically supported in the hover:

In theory, the full extent of MarkdownString could be supported in the hover, but I think there's a lot of MarkdownString that doesn't make sense for the label:

• Headings
• Table
• Code block
• Quote block
• Lists
• Images
• Links? (since that would interfere with click event handler)

Which leaves:

• Strikethrough
• Bold
• Italics
• Inline code

I wonder if that would cause confusion.

[lukaschneider]

Hey,
I am currently working on an extension which enables a user to open packet traces in vscode. While prototyping I came across this issue.

Having an option to use a monospaced font would improve readability a lot in my case.

Before:

After: