@Terry, code updates can be followed on https://github.com/upendra-k14/pip_gui/tree/dump_code

Please review the code in dump_code branch. For now, only pip_gui_v3.py is relevant. 

1.  I had doubt about including a private module from pip ( "pip._vendor" ). As this module contains a lot of important utilites I have included it by copying the "_vendor" module in my package and changed all the package references of 
"pip._vendor" to "pip_tkinter._vendor" to make it work. Since, it was a private module, I included it by copying it. 

One more reason is that pip has mentioned this module has immutable. There are very less chances that further changes in this module will be introduced in future.

2.  Except a few complex commands like install, I have planned to inherit the pip command classes. For example, I have inherited the pip.commands.SearchCommand class from pip and overrided the "run" method. It helped me to give finer control over the search results. 

For example,

Now we can retrieve all previous versions of a package ( which is not provided by pip ) and search results can be directly obtained in form of tuple lists without parsing the output.
But, I think doing something similar for pip.commands.InstallCommand is very difficult. Therefore, for now I have chosen to use "runpip and pip.main" for pip install command.