text: Title: The animation window didn't show up
  Body: I typed 'manimgl' and pressed the key 'Enter', this is what happened to my terminal.
  My terminal just waiting, with the cursor flashing continously.
  ![2022-01-25 20-00-53屏幕截图](https://user-images.githubusercontent.com/84609589/150973385-6b7d3dbe-6771-4da8-afb6-a40147bc6fdb.png)
  'Maybe it is loading now, I just to wait for some time', I thought, but through an hour (or longer), nothing happened, and the terminal just waiting, waiting for me to type some string, like a text edit software.
  ![2022-01-25 20-32-34屏幕截图](https://user-images.githubusercontent.com/84609589/150977651-4fa0afec-2047-40da-926d-d6ad8693d60f.png)
  ===Environment Config========
  System: Ubuntu 21.10, x64
  Python: 3.9.7
  Manim: 1.3.0
  ===Problem Description========
  It should pop up the animation window and the terminal should enter interactive mode, but in this case the animation window didn't show up.
  ===What I have done==========
  I have installed the manimgl (using the command '`pip install manimgl`'), and other softwares (like TeXLive, FFmpeg) also have been installed.