Godot: Sub Viewports don't render anything

[Wolf17777]

Operating system or device - Godot version:
Windows 7 64bit - Godot 3.0 alpha1

Issue description:

Sub Viewports don't render anything.

Steps to reproduce:
-Create new project
-Add Control node and resize it so its visible in the game
-Add Viewport node to the Control node
-Add Something to the Viewport node, e.g. a Button
-Launch the game. The Button should be visible, but isn't.

[reduz]

oh, you need to use ViewportContainer, putting a viewport in a control is no longer supported.

[toger5]

Why do the viewports (without container) exist than? if they don't work alone. isn't that bad ux?
would it be possible to just remove vieport container and the viewport does everything the container handled before ?

[bojidar-bg]

@toger5 You can use them as standalone render targets, without rendering them to the screen.

[toger5]

@bojidar-bg that makes sense! Ty

[eiszfuchs]

It might be a good idea to update the documentation then. 🤔
https://godot.readthedocs.io/en/latest/tutorials/viewports/viewports.html#sub-viewport