Fractional Scaling shows a black bar on secondary monitor

[roland]

The right part of the external screen shows a black bar when using fractional scaling.
This started happening this week.

Somebody else is also experiencing this problem:
* [ubuntu discourse post](https://discourse.ubuntu.com/t/x11-hidpi-scaling-available-for-testing-on-disco/10293/23)
* [photo](https://ubuntucommunity.s3-us-east-2.amazonaws.com/original/2X/5/509069037c78c1e5b461e526236ffeb207de1025.jpg)

Attached monitors:
* External 4K
* Laptop: qhd

Tried connection types:
* HDMI (30hz),
* HDMI over usb-c
* DP over usb-c

Fractional scaling was set up in this way:
`gsettings set org.gnome.mutter experimental-features "['x11-randr-fractional-scaling']"`

It doesn't seem to be monitor related.
It works when:
* using wayland
* turning off fractional scaling
* during boot and login

Installed software:
* ubuntu 19.04
* Gnome 3.32.1

[Sebastien Bacher (seb128)]

Thank you for your bug report. Not sure what desktop you are using but that screenshot isn't Ubuntu. Those HiDPI daemon settings don't exist in GNOME/Ubuntu.

Does it happen on Ubuntu as well? Could you add a journalctl log after getting the issue?

[roland (roland-micite)]

I don't know about the HiDPI deamon. It's not my picture.
I did however experience the same problem.

The software used is a regular ubuntu 19.04 with the default window manager.

At the moment I can't connect the monitor. I'll try to get a journalctl log after experiencing
the issue when I do use the monitor again.

[Daniel van Vugt (vanvugt)]

Please run:

  apport-collect 1852864

to send us more information about the machine.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 19.04 (disco) reached end-of-life on January 23, 2020.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in and change the bug status to Confirmed.

[roland (roland-micite)]

Thank you for going through this issue.

I just tested the combination 19.10 with HDMI and the bug doesn't appear.
I'll try again later with DP over usb-c.

[roland (roland-micite)]

Let's close this issue. I can't reproduce this on Ubuntu 19.10.

One thing to note: The problem only showed up after some time with Ubuntu 19.04.
It worked for like a week before the problem arose.