Camera2D in a viewport while running as an editor plugin doesn't work

[Nukiloco]

Godot version:
Godot v3.1.2

OS/device including version:
Windows 10

Issue description:
Whenever running as an editor plugin, Camera2D nodes won't work in a separate viewport.

Steps to reproduce:

1. Make an EditorPlugin.
2. Make a scene with a Viewport, Sprite and a Camera2D node.
3. Add a script to make the Camera2D node move around.
4. Run the editor plugin and try to move the camera around.
5. The Camera2D node doesn't work at all.

Minimal reproduction project:
https://github.com/Flairieve/GraphicsEditor/

[novemberist]

I don't think your Camera2D script will actually run in the editor, unless you make it a tool, too. At least if I understand this article correctly: https://docs.godotengine.org/en/3.1/tutorials/misc/running_code_in_the_editor.html

If you add the tool keyword, the camera actually moves within your viewport in the editor. However, in that case the Viewport doesn't scroll with it (probably because it is not the active camera in the editor viewport). I think this might be an issue with your implementation, rather than a bug. Wouldn't know how to fix this, though.

[Nukiloco]

The camera script isn't a tool script on purpose so it doesn't run in the editor scene. I have tried it before as a tool script and that didn't work also. I think it's something that has to do with using viewports in the editor.

[bojidar-bg]

You might have to use a custom script which modifies the viewport's "canvas_transform", as Camera2D is specifically made to not run while Engine.editor_hint is true.

[Nukiloco]

If that's the case then shouldn't camera nodes be allowed to run in the editor if they are under a viewport? I feel like it's more tedious to remake the entire camera script just to move around in a viewport in the editor.

[bojidar-bg]

The thing in the middle of the editor screen is already a viewport, so this would require some changes to how viewports work.

[Nukiloco]

Wait so the editor can only run a couple of viewports at a time?

[Nukiloco]

Even with that, you should be able to use a viewport with a camera in it as an editor plugin.