LightDM is broken when using a dock with HDMI cable connected on Pinephone.

Describe your issue

What's the expected behaviour?

When I click on 1 in lightdm, 1 is clicked.

What's the current behaviour?

When I click on 1 in lightdm, usually 3 is clicked, sometimes it clicks on 2 and sometimes 1. video

How to reproduce your issue?

1. power off the phone
2. connect the dock from Convergence Edition to the phone and connect it with an HDMI cable to a monitor.
3. power on the phone

What device are you using?

Pinephone CE postmarketOS edition 3GB/32GB

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• stable (v20.05 branch)

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in dd-mm-yyyy format)

17-09-2020

Additional information

I can get it to behave this way every time I have a dock with an HDMI cable connected. On the other end of the cable is a monitor, but it is not working right now (#735 (closed) ), however I believe the phone sees it as a connected screen.