Custom theme in Project Settings causes Controls to render incorrectly.

[ghost]

Godot version:
3.0

OS/device including version:
Linux 64 bit.

Issue description:
Setting a custom theme causes some Controls to be invisble except for a bit of poorly-rendered text that says "ERROR". So far I've confirmed this only with the several controls that are in the example project. I haven't tested further but I suspect it probably affects all Controls.

Steps to reproduce:

• Make a theme resource
• Add a default font to it
• Save it as a .tres
• Project > Project Settings > Gui > Theme
• On the row that says Custom, click the folder icon on the right, and click File
• Navigate to the .tres file you just made.
• Run your project and see messed up widgets
• Go back into Project Settings and clear the custom theme
• Your widgets are back!

Or just use the minimal example project! Extract, open, run.

Minimal reproduction project:
CustomThemeBug.zip

[AaronWizard]

I have this error too. This is what happens when I have a label while trying to use a custom theme.

I'm not sure if the label's black text is a bug or if I just missed something in my theme. I'm more concerned about the "ERROR" that appears in the background. I've seen this with multiple font TTFs.

My own example project:
themetest.zip

[Mintormo]

This is not a bug. When you make empty theme, values of styleboxes in control is null so It's used default style value. It's maked from .png with "Error" text.
Here: scene/resources/default_theme/default_theme.cpp: 872
I think this issue is worth to close. Else It's maybe change default style to empty style box.

[ghost]

Else It's maybe change default style to empty style box.

That definitely needs to happen. Right now, for example, I have a HScrollBar. I don't want to have increment or decrement icons for it, so I left them blank. But instead it looks like this:

It's kind of dark, but you can see the problem. I don't think it should be necessary to manually set every stylebox that you don't intend to use.

[AaronWizard]

I agree. It wasn't clear to me that controls all have a style box, even labels, and that a null style box causes the "error" background.

[reduz]

I am wondering whether the error icon should just be a small empty one.. is there much point on showing it?