Only store _edit_use_anchors_ metadata if value is not the default

[Calinou]

master version of #58254.

The default value is assumed to be false, so this metadata only needs to be stored if the value is true.

This closes #57862.

Bugsquad edit (keywords for easier searching): edit_use_anchors

[rakkarage]

The pull request build seems to work for me. New scenes no longer have that setting written into them it seems.

But during testing I ran into another issue. You cannot undo a toggle of the anchor button? Maybe I will open a new issue?

Thanks.

[Calinou]

But during testing I ran into another issue. You cannot undo a toggle of the anchor button? Maybe I will open a new issue?

Does this happen without this PR?

[rakkarage]

Yes, in 3 and 4.

• Make new Control scene and drag/move control then toggle use anchors
• Scene->undo un-moves the control instead of the toggle

[Calinou]

Yes, in 3 and 4.

* Make new Control scene and drag/move control then toggle use anchors

* Scene->undo un-moves the control instead of the toggle

Use Anchors is an editor-only action, so I don't think it makes sense to be tracked in undo/redo. It would be like tracking selection of 2D/3D nodes in the editor as an undoable action. There is no project data being changed here, only data being read. Most other applications don't track such operations in their undo/redo state.

[rakkarage]

Ya sorry, I agree, I guess I still thought it was doing the the _edit_use_anchors_ stuff :)
Thanks.

[aaronfranke]

Really this should be moved out of the scene file. We don't need to store local editor specifics in version-controlled scene files, this kind of data would have a better home in the .godot/editor/ folder.

[YuriSizov]

Really this should be moved out of the scene file. We don't need to store local editor specifics in version-controlled scene files, this kind of data would have a better home in the .godot/editor/ folder.

Do we have examples of other per-node properties stored in there? This is similar to _edit_lock_, which is also stored with nodes at the moment. There is also a question of how and if we should allow editing this programmatically, so that, say, a plugin could create a node and mark it to use anchors by default.

I agree in principle, but there is also an argument to be made that this needs to be synced and needs to be attached to the node.

[YuriSizov]

This PR needs a rebase/remake since the relevant code is now in control_editor_plugin.cpp. It should mostly be the same, IIRC, but I'd still appreciate an update before reviewing it.

[YuriSizov]

The change seems to be straightforward.

@rakkarage has a point though. In one case we save this editor-only flag as a part of UndoRedo, and in another we don't. But that's existing behavior, so I think it's a non-blocker for this PR.

[akien-mga]

Thanks!

[akien-mga]

Could use a dedicated backport for 3.x as this code has changed somewhat.