This mod provides an API to add custom settings panels to the settings dialog.

API documentation

Example:

public override void StartClientSide(ICoreClientAPI capi)
{
    GuiCompositeSettingsEx.AddPanel("testpanel", (settings, on) =>
    {
        GuiComposer composer = settings.ComposerHeaderEx("testpanel", "testpanel");
        // Add your GUI elements here using standard UI elements.
        // Be aware that the header is 75.0 pixels high.
        
        composer.EndChildElements(); // title bar
        composer.Compose();
        settings.LoadComposer(composer);
    };
}