Fix duplicating multiple nodes at different depths in SceneTreeDock

[TheSofox]

Fixes #84333.

Duplicating multiple nodes at different depths seemed to put all the new nodes on the same level, which was counterintuitive. Also, undoing this operation was bugged.

I've fixed it so that each duplicated node appears next to the node it was duplicated from at whatever depth it was at. This also fixed the Undo functionality.

[KoBeWi]

This changes how nodes on the same level are duplicated:

godot.windows.editor.dev.x86_64_dmAeG1gXuZ.mp4

vs old

godot_Hsbxsczcj5.mp4

I don't think that's expected behavior. Especially the order is garbled (reminiscent of this old issue #38162, which the code you removed fixed)

[TheSofox]

Question: You duplicate (both nodes, same level):

• TypeA1
• TypeB1

Is the desired result:

• TypeA1
• TypeA2
• TypeB1
• TypeB2

or:

• TypeA1
• TypeB1
• TypeA2
• TypeB2

[KoBeWi]

I'd say the latter.

In case of

• TypeA1
• TypeA2

Expected result is

• TypeA1
• TypeA2
• TypeA3
• TypeA4

In your example, the latter result is consistent with the above.

[TheSofox]

Understood, but I need to ask another question about desired behaviour:

• AudioNode
• Player Node
• AnimationNode
• Particle Node

You select AudioNode and AnimationNode (I'm assuming order you select them in doesn't matter, let me know if it does) and duplicate. This obviously creates two more nodes (AudioNode2 and AnimationNode2) but where are they positioned?

[KoBeWi]

Currently you'd end up with

• AudioNode
• PlayerNode
• AnimationNode
• AudioNode2
• AnimationNode2
• ParticleNode

I think you should keep the current behavior for nodes on the same level and only fix duplication with different parents.

[TheSofox]

Understood. Thank you for explaining.

[TheSofox]

Amended PR and pushed. Like you asked, it sticks with current behavior for nodes on the same level, but still handles having nodes with different parents.

[akien-mga]

Thanks!

[akien-mga]

Cherry-picked for 4.2.2.