There isn’t a known optimum, but I’ve tried making GUI from scratch many times and am gradually getting better at it. This is a good opportunity for me to let out my thoughts all at once - r/gamedev

Anyway, if I were doing a new game GUI again, I would start with a “debug” gui like Dear IMGUi that perhaps doesn’t have skinning but has easy placeholders. Good layouts take a few iterations, and trying to skin early is wasteful.

• Basic functionality for text, sprites, and layout. Word-wrapped proportionate text is quite a large time sink.
• Ability to keep state for lists and scrolling list views.
  • if you want a fully-fledged and optimized list view that supports arbitrary sizes of inner elements
• Ability to safely compose drawing commands
  • used a single stack with default behaviors for transforms, scaling, etc and then extended it by adding an XML domain-specific syntax that let me safely describe widget parameters and stack levels, and do some basic goto-style flow control.
• Ability to distinguish between layout, collision and rendering stages, when it’s relevant.
  • n imgui this can be accomplished more directly by running the children first, only getting bounds from them, and then running them again later.
• Ability to describe elements with appropriate units and relative positions.

Alive C++ UI Libraries

• Dear ImGui