Bug 97818

I believe the issue is related in some way to the Linux kernel - as I could test 4.7.2-201 vs 4.6.7-300 on the same laptop and the latter version has no issues - but the people on Linux kernel's bugzilla bounced me away and asked to post here instead (https://bugzilla.kernel.org/show_bug.cgi?id=156781).

The following has been tested using Fedora 24 on a Thinkpad T450s (Intel Core i7-5600U, Intel HD Graphics 5500).The docking station is Lenovo's "90 W Pro Dock", connected to a Dell UltraSharp U2913WM monitor. The laptop is configured to ignore if the lid is closed. 

To reproduce the issue:

a) turn on laptop connected to docking station with the lid closed, and proceed until logging into Gnome
b) "hot-undock" from the docking station and open the lid

In kernels up to 4.6.7-300 the display automatically has switched to the laptop's.

In kernel 4.7.2-201 nothing happens and the laptop's display is dark, as if the laptop was still trying to use the monitor connected to the docking station.

c) close the lid (this correctly does not suspend the laptop) and "hot-dock" back to the docking station

In kernels up to 4.6.7-300 the display automatically switches back to the external display.

In kernel 4.7.2-201 the behaviour is erratic. Sometimes it activates the external display back, some other time it does but the resolution is wrong etc.

The Xorg packages versions are:

$ sudo dnf list installed | grep xorg
abrt-addon-xorg.x86_64                2.8.2-1.fc24                 @@commandline
xorg-x11-drv-ati.x86_64               7.6.1-3.20160215gitd41fccc.fc24
xorg-x11-drv-evdev.x86_64             2.10.3-1.fc24                @@commandline
xorg-x11-drv-fbdev.x86_64             0.4.3-24.fc24                @@commandline
xorg-x11-drv-intel.x86_64             2.99.917-24.20160712.fc24    @@commandline
xorg-x11-drv-libinput.x86_64          0.19.0-2.fc24                @@commandline
xorg-x11-drv-nouveau.x86_64           1:1.0.12-4.fc24              @@commandline
xorg-x11-drv-openchrome.x86_64        0.5.0-1.fc24                 @@commandline
xorg-x11-drv-qxl.x86_64               0.1.4-7.fc24                 @@commandline
xorg-x11-drv-synaptics.x86_64         1.8.3-2.fc24                 @@commandline
xorg-x11-drv-vesa.x86_64              2.3.2-24.fc24                @@commandline
xorg-x11-drv-vmmouse.x86_64           13.1.0-3.fc24                @@commandline
xorg-x11-drv-vmware.x86_64            13.0.2-11.20150211git8f0cf7c.fc24
xorg-x11-drv-wacom.x86_64             0.32.0-2.fc24                @@commandline
xorg-x11-font-utils.x86_64            1:7.5-31.fc24                @@commandline
xorg-x11-fonts-Type1.noarch           7.5-16.fc24                  @@commandline
xorg-x11-proto-devel.noarch           7.7-19.fc24                  @@commandline
xorg-x11-server-Xorg.x86_64           1.18.4-4.fc24                @updates     
xorg-x11-server-Xwayland.x86_64       1.18.4-4.fc24                @updates     
xorg-x11-server-common.x86_64         1.18.4-4.fc24                @updates     
xorg-x11-server-utils.x86_64          7.7-19.fc24                  @@commandline
xorg-x11-utils.x86_64                 7.5-21.fc24                  @@commandline
xorg-x11-xauth.x86_64                 1:1.0.9-5.fc24               @@commandline
xorg-x11-xinit.x86_64                 1.3.4-11.fc24                @@commandline
xorg-x11-xkb-utils.x86_64             7.7-17.fc24                  @@commandline
$ 

Other notes:
- the issue can be reproduced also starting with the laptop undocked
- when having the issue, suspending the laptop and waking it back up sends the video to the correct display
- after having the issue, shutting down hangs on 4.7.2-201 but completes successfully with 4.6.7-300

Sorry if I did not attach any log files etc. but I'm a noob and I wouldn't know where to start, but please ask and I will try to provide you with what you need.