The GUI I am trying to re-create: 

 

 

My questions are:

 

How would I relatively position buttons and labels next to each other? (Right now, manually positioning each element with absolute value is painful and unintuitive)

How would I add a listbox area that is scrollable?

How to make sure that my GUI positioning is fine on different resolution?

 

That's pretty much it.

 

Try Creating a ScaledResolution 

new ScaledResolution(this.mc); 

And then use getScaledWith and getScaledHeight for calculations. At least this works for me in Overlay Rendering(although I get the ScaledResolution from an event there)

If you're using a GuiScreen, setting the xSize and ySize will correctly set the guiLeft and guiTop variables in your GuiScreen, which represent the coordinates of the top-left corner of your GuiScreen. You can use those variables to determine positions of buttons and text.

1 hour ago, ArmamentHaki said:

Try Creating a ScaledResolution 

new ScaledResolution(this.mc); 

And then use getScaledWith and getScaledHeight for calculations. At least this works for me in Overlay Rendering(although I get the ScaledResolution from an event there)

 

39 minutes ago, larsgerrits said:

If you're using a GuiScreen, setting the xSize and ySize will correctly set the guiLeft and guiTop variables in your GuiScreen, which represent the coordinates of the top-left corner of your GuiScreen. You can use those variables to determine positions of buttons and text.

 

Thanks to you both. Looks like something that I would need. How do you place an element next to each other with offset? Like a label next to a textfield or a button next to another button. And do I need to keep a reference to each individual element? 

2 minutes ago, diesieben07 said:

You are asking for a layout engine in Minecraft. There is no such thing. You need to position things manually with absolute offsets.

Is that how the Configuration GUI was done? Because it looks rather nice and properly size/aligned and all of that.

I think there should be something in Forge that makes this easier or a helpful post in Common issues, as loads of people have the problem that their GUI resizes on changing the the scale. 

15 minutes ago, diesieben07 said:

Look at the code for it

It's messy to look at the code. A lot of Configuration related stuff and stuff that makes no sense.

2 minutes ago, diesieben07 said:

You just discovered why GUIs suck.

Yep digging deeper, it seems like Minecraft have no love for GUI. Even mods like refined storage and AE2 seems to use absolute positioning and a lot of headache inducing positional calculation. I will most likely switch to commands instead.