Qt application - open one process only

I have Qt GUI application which I want that the user will open one only. I want that if the user will click first time on th exe - it will open the application and when he will click it again it will open the first one.

i don't want to do it with QtSingleApplication. I 开发者_StackOverflow社区want to know exacly how to open the GUI on the second time.

Help me please!

Even if you don't want to, QtSingleApplication is what works. If you want to learn how it is implemented, you can always read the source code.