Add an editor_description property to Node for documentation purposes

[Calinou]

It is implemented using editor-only metadata, in a way similar to edit locking or Position2D gizmo extents.

This closes #2082.

Caveats

• The tooltip is only updated when the scene is reloaded. How could this be fixed efficiently?
• Due to Instanced scenes share their metadata if the saved PackedScene contains saved metadata #29189, comments written on a non-root instanced scene will be lost when the scene is reloaded. Comments written on the root node of the instanced scene will be preserved, but this means it will be shared across all instances.

Preview

Edition in the inspector

Display in a tooltip in the scene tree dock

[bojidar-bg]

Can/should this be added to the Node's metadata instead?

[Calinou]

@bojidar-bg The comment property only sets/gets metadata, it doesn't actually store the value in the property, just like in #28390.

It could be made into a metadata-only value (without an associated comment property). In this case, we'd need to expose it in the Inspector somehow (or somewhere else). This would have the upside of not having to break compatibility 🙂

[akien-mga]

GraphNode's comment property was renamed to comment_node to avoid naming conflicts.

Should it be named description so that it doesn't need to break compat?

[bojidar-bg]

Or editor_comment, or editor_description, so it clear that the property is editor-only.

[Xrayez]

Should it be named description so that it doesn't need to break compat?

Just added this for one of my custom resource node recently. 😃

[Xrayez]

It could be made into a metadata-only value (without an associated comment property). In this case, we'd need to expose it in the Inspector somehow (or somewhere else). This would have the upside of not having to break compatibility 🙂

I've made some table UI with which you can pass an array of properties to be displayed for each column in the table, rows being the actual nodes/objects etc. So having a comment or description property (not metadata) would allow me to generalize this down to using get_property_list, so my concern is whether this method could actually return metadata for object or whether I'd to have add an additional check just for this manually. An example of how I'm using this:

var objects = [...]
table.create_from_data(objects, ['description', 'count', 'enabled', ...])

[akien-mga]

Or editor_comment, or editor_description, so it clear that the property is editor-only.

So should we go with editor_description?

[Calinou]

@akien-mga Done 🙂 This PR should no longer break compatibility now.

[akien-mga]

Thanks!