DDSOS adds additional input box right next to the every drop-down found. It creates a link between input box and drop-down, so data selected are displayed in the input box, but also data edited in the input box will change the drop-down. DDSOS is using datalist, so easy search and selection of item is possible.
Also if item entered into input box matches the drop-down list, it will have green colour. If no match is found, it will be red. If multiple matches are found, it will be blue.
The real value of the drop-down selection is transferred into a tooltip of the input box.
Extension supports per-site selection thanks to DFWP add-on.
To activate the add-on for a particular web-site (domain), click on the add-on Icon in the firefox toolbar and click on Save button.
You can edit all enabled web-sites in the main Firefox Tools/Add Ons and Themes/Extensions/DDSOS/Options menu.
https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_option
But you need to first click on plug-in Icon and hit the Save button.