Problem with shader editor project

Hi
I working on project like https://shdr.bkcore.com/ as my graduate project
I step on 2 major problems
1st one is with ( i think ) depth buffer - sometimes surface in back display in front

(look for code for object class ) https://controlc.com/7f9875e7



Second one is in my main class
I want to dispay figures within my main window but whatever i try objects display in second window

here part of main class - https://controlc.com/25a93220

I will be gratefull for help and also i know my code is buggy :(