"OpenGL shader" selection box looks misleading when GDI backend is selected

[eierfrucht]

As the title suggests: https://i.postimg.cc/5Nryxp3J/GDI.png

Steps to reproduce:

1. Select OGL
2. Pick a shader
3. Switch to GDI
4. Shader selection box is still shown and lets you pick stuff

Switching to Direct3D 9/12 replaces the selection box with a different one (DX shader apparently)

Following the same logic GDI should have no shader selection box at all; otherwise novice users are wrongly hinted that GDI somehow ought to support GLSL shaders--but none appear to work

[FunkyFr3sh]

Yeah, I'm still not sure about this one. I had the shader selection disabled first, but then people don't understand why it's disabled. Then I changed it so when you switch the shader it would automatically change the renderer to OpenGL

[eierfrucht]

A greyed-out box can look confusing, but removing the box completely for unsupported renderers, wouldn't that look self-explanatory?

There also could be a plain text string like "GDI doesn't support shaders! Select a different backend for shader support." plastered in place of the shader selection box as long as GDI is selected.