[PyQt] How to open a program with python without freezing

[LavaCreeperKing]

Hi, can someone tell me how I can open a program with python without it freezing my program? What I am trying to do is create a program with some quick command buttons that allow me to open other programs or files. The problem is that when ever I open a program it freezes my GUI window until I close the opened program. The only fix I have found is to call explorer then use explorer to open the program or file. This works except for one problem. Explorer opens files with the default program that is registered to open the file with, but I want to be able to choose the program that opens the file. For example, I want to edit a .png file in gimp so I don't want to have the .png file open with photo viewer or paint. How would I get it to open with gimp? So to solve the windo freezing problem I created a new thread to open the programs with and that prevents my GUI window from freezing, but when I open a program the thread then freezes and I can't open any more programs until I close the first one. How do I open programs/files without my program freezing?