Convert Type: Greyed

Hi does anybody have the idea for the Greyed convert type?
In the wiki page, there is no description about it.

wiki.synfig.org/Convert#Greyed

Late, I know. But just to document the answer for this question as I made it myself these days:

According to commit message:

Add ValueNode “Greyed” for making ducks uneditable.

It doesn’t seem to work as originally intended.