Steps to replicate the issue (include links if applicable):

• I want to add a new tester to the multiply function, i.e. go here https://wikifunctions.beta.wmflabs.org/w/index.php?title=Special:CreateZObject&zid=Z20&Z20K1=Z10058
• click "select function" under "call"
• click into the field ZObject under Function
• select the multiply function, ie. by typing multiply and select the respective value from the drop down (Z10058)

What happens?:
We get the two arguments, but the literals are "closed", there is nothing I can enter.

What should have happened instead?:
One should be able to actually enter the literals, it should look like this

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):

Workaround: if I use the modeselector to change to reference and then back to the literal, it works.