Found some references to what seem to be the same problem on askubuntu
http://askubuntu.com/questions/531897/ubuntu-14-04-laptop-screen-shaking-no-problem-on-external-monitor-hdmi-len
http://askubuntu.com/questions/562760/ubuntu-shaky-display-problem
Seems like I have to update the kernel. (IE. some updates are missing in the 3.16.0-xx kernel)
Found some references to what seem to be the same problem on askubuntu
http:// askubuntu. com/questions/ 531897/ ubuntu- 14-04-laptop- screen- shaking- no-problem- on-external- monitor- hdmi-len
http:// askubuntu. com/questions/ 562760/ ubuntu- shaky-display- problem
Seems like I have to update the kernel. (IE. some updates are missing in the 3.16.0-xx kernel)