Close MacBook when using ext. Screen? I have got a MacBook pro with retina display.

Now I want to use a trackpad and keyboard and an external screen on the MacBook.

Can I close the MacBook now to keep working or does this initiate the standby so I can't use the external devices anymore?
If you have an external display attached with an external mouse/trackpad and keyboard, closing the lid will not put the machine in standby mode. You can keep using the computer with those devices. 

Check this Apple link to read the official statement about it. 


  Requirements for closed display mode:
  
  
  Power adapter
  External keyboard, mouse, or trackpad
  External display