When I plug in an external monitor, all windows of my main screen are moved to the external screen (extended monitor setting).

This is annoying because :

1) window placement is messed every time I move the laptop ;

2) it causes confidentiality issues when you do it in front of a boost or a classroom : all applications appear on the screen that is aimed to the presentation.



Reproducible: Always



Expected Results:  
Window placement should be preserved on the main screen and the external monitor should be blank after plugging.