When I right click on the desktop and select desktop settings, in the relevant screen that comes up, the drop down lists do not follow the system colour themes (in this case, "Fry & Leela" colours, with Breeze Dark). 

For example, clicking on "Wallpaper type" will make the drop down list appear, but its background will be white, not the dark grey in other drop down lists of system settings. The same goes for every drop down list in this module (either in "Wallpaper" or in "Mouse Actions").

Other drop down lists in system settings have the expected colours. I think the problem is the background colour, the text colour seems to be correct.  

Reproducible: Always

Steps to Reproduce:
1. Select a dark theme like Breeze dark Right click on desktop and select "Desktop settings"
2. Click on the drop down list for "wallpaper type"


Actual Results:  
The list that appears does not have the same colours as other drop down lists (the background is white instead of the theme's.

Expected Results:  
The list should have the same colours as the rest of the drop down lists in the system.