🚀 go-pugleaf

I have seen responses to this info request, and I expect it will be very
helpful to me as well since I was thinking of writing an application to
run with various graphics cards.  Thanks.

I would like to ask a realted question:

When I look at various games and applications that run on PC's, I get
the impression that the application writers invent their own homebrew
user interface system.   That is, the pop-up menus and dialogs, etc
appear to be custom built rather than implemented through some standard 
set of library routines.

The only standard software that I am aware of (although never seen or used)
is Microsoft Windows, which I EXPECT has these user interface features.  
However, I also expect MSW is used to manage MULTIPLE programs running under 
DOS in different windows whereas what I want is a somewhat SIMPLER set of 
UI tools (popups, dialogs, etc) that I can use within a SINGLE application 
on the PC.

Does such a library exist ?    Price ?
Thanks in advance.