title: PyQt5 Designer is not working: This application failed to start because no Qt platform plugin could be initialized
body: <p>i have a problem with PyQt5 Designer. I install PyQt with -pip install PyQt5 and then -pip install PyQt5-tools
  everything OK. But when i try to run Designer it open messagebox with error: This application failed to start because no Qt platform plugin could be initialized!
  how to deal with it?</p>