There are many iterations of this question, few with actual working answers, so after a few hours of trying to get it working on my machine, I will post my solution.
How do I configure my Ubuntu laptop to use an external monitor as well as the built-in screen, while allowing me to drag windows across the boundary?
This is likely to be hardware-dependent, so your mileage may vary.
My hardware is:
HP Zbook 14, with dual Intel and ATI Radeon HD 8730M GPUs.
The relevant lines of sudo lspci are
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b)
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M]
I'm running Ubuntu 14.04, and the output of fglrxinfo is
display: :0 screen: 0
OpenGL vendor string: Advanced Micro Devices, Inc.
OpenGL renderer string: AMD Radeon (TM) HD 8500M/8700M
OpenGL version string: 4.3.12798 Compatibility Profile Context FireGL 13.35.1005
After much playing around with xinerama options and so forth, the following xorg.conf file works for me
Section "ServerLayout"
Identifier "amd-layout"
Screen 0 "aticonfig-Screen[0]-0" 0 0
Option "Xinerama" "off"
EndSection
Section "Monitor"
Identifier "aticonfig-Monitor[0]-0"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
HorizSync 30.0 - 60.0
VertRefresh 50.0 - 60.0
EndSection
Section "Monitor"
Identifier "aticonfig-Monitor[0]-1"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
HorizSync 30.0 - 60.0
VertRefresh 50.0 - 60.0
Option "RightOf" "aticonfig-Monitor[0]-0"
EndSection
Section "Device"
Identifier "aticonfig-Device[0]-0"
Driver "fglrx"
BusID "PCI:3:0:0"
Screen 0
EndSection
Section "Device"
Identifier "aticonfig-Device[0]-1"
Driver "fglrx"
BusID "PCI:3:0:0"
Screen 1
EndSection
Section "Screen"
Identifier "aticonfig-Screen[0]-0"
SubSection "Display"
Virtual 4000 1600
EndSubSection
DefaultDepth 24
EndSection
I think that the most important points are that there are two "Monitor" sections: One of which has the "RightOf" option, and just one "Screen" section. Many of the "solutions" I came across in my hunt had two screens, and this is what the command sudo aticonfig --intial=dual-head does by default.
ARandR will allow you to do this. It is available through the software centre. It is a GUI for configuring external monitors. It will allow you to extend your laptop screen out to an external monitor and drag windows across. I have used it for my TV.
Go to the software centre and search for ARandR. Download and open it. It should automatically detect any ext monitor that is plugged in. LVDS1 will probably be the name of your laptop screen, while VGA1 or HDMI1 will probably be the name of the ext monitor. You can position the ext monitor to any side of your laptop screen by clicking and dragging the appropriate monitor. Having them overlapping completely will have the same display showing on both monitors, while having them side by side will extend your usable space over the two monitors. You can even have them slightly overlapping if you so wish. Play around a little. Once you have gotten a configuration you like click the 'tick' symbol. and it will be applied.
When using the system afterwards, should you wish to drag a window to the ext monitor, simply click on the titlebar and drag to the side of your laptop screen that you placed the ext monitor on and you will see your window begin to appear on the ext monitor.
sudo apt-get install arandr, although you get the same functionality (with a better UI) using the 'Monitor Preferences' dialog that is installed by default.
Nov 10, 2014 at 3:16
amdcccleto select "Power-saving GPU" (Intel) when you want to use multiple monitors. In my case, the Intel is just as fast anyway (for basic 3D w/o anti-aliasing).