Display dialog goes haywire after unplugging an external monitor
## Submitted by Yousuf Philips `@philipzae`
Assigned to **Xfce Bug Triage**
**[Link to original bug (#16729)](https://bugzilla.xfce.org/show_bug.cgi?id=16729)**
## Description
Steps:
1. startup with an external monitor
2. open up display dialog
3. unplug external monitor
4. dialog shows to headers and UI elements are missing until hovering over them
Tested on Xubuntu 19.10
Version: 4.14.1
issue