Settings UI lacks concept of inherited default value

[jrieken]

re #57304

• open settings UI
• locate 'Suggest Font Size'
• notice how the UI shows 0 which isn't true - the default value is the font size of the editor.

[roblourens]

0 means "the font size of the editor" but the value itself is 0. If we want to change that, the default could be null which would show in the UI as an empty input box. How would you display the real default?

[jrieken]

Well, it should show 12 or whatever the editor font size is. The fact that we internally treat 0 as 'use editor font size' is an implementation that leaks into the UI. I think a user that didn't implement the suggest widget won't understand this

[roblourens]

Do you know of any other settings with similar behavior that fall back on the value of another setting? Would need some metadata or something for this.

[jrieken]

Yeah, metadata is needed. When defining a setting we should be able to refer to another setting which defines its default

[chrmarti]

Or just add (0 to use the editor's font size) to the description.

[roblourens]

I added a note to the descriptions for those two settings.

[rzhao271]

We currently have the ability for extensions to override the default value of other settings with contributes.configurationDefaults.
This feature sounds like we want settings to "look to" other settings for the default value.

#57330 (comment) is nice, because we avoid having to change the setting to use nullable types.

Moving this to backlog candidates.