Enable editing of controls inside viewports in editor

[Black-Cat]

Fixes #79289

I've tested:

• Selection
• Box Selection
• Anchors
• Moving
• Rotating
• Scaling
• Pivot
• Temporary pivot
• Smart Snapping
• Grid Snapping
• Helpers
• Focus

Bugsquad edit:
Fixes #20619
Fixes #60088

[KoBeWi]

Looks like #61873, but actually working.

[KoBeWi]

Tested various 2D editor interactions and didn't see any obvious side-effects. It works surprisingly well.

[kitbdev]

Some nodes have an incorrect gizmo position when in a Viewport not at the origin, like position indicators for Node2Ds or handles for Line2D, CollisionShape2D, etc.

Selecting works and using the handles works, they're just offset and not rotated or scaled.

Also, If the viewport gets rotated or scaled, using the move or scale tools aren't correct, though the resize gizmos are fine.

[kitbdev]

The issues I mentioned before are all fixed. Looks good!

[Calinou]

Tested locally (rebased on top of master 0eadbdb), it mostly works as expected.

On GUI in 3D, I can see the editing controls and interact with them, but nothing appears in the 2D editor viewport:

All nodes are set to be visible in the 2D scene tree.

I can see the preview in the inspector though:

[kitbdev]

On GUI in 3D, I can see the editing controls and interact with them, but nothing appears in the 2D editor viewport:

They also do not appear in 4.3 and in master. This is intentional since SubViewport do not draw anything by themselves. In that scene, the SubViewport is rendered to a MeshInstance3D, so it will only show in the 3D Editor.

So instead, the nodes in a SubViewport without a SubViewportContainer should not be selectable or editable in the canvas editor.

[akien-mga]

Thanks!

[KoBeWi]

Unintended consequence is that you can move nodes outside the current scene:

A3lGkciR1z.mp4

Granted, you need a custom EditorPlugin to select such nodes. We could use in_part_of_edited_scene() to prevent this, but it's not really a problem I think 🤔