Pluma Used to Store Cursor Location - but where?

In my running 14.04 desktop, Pluma remembers the last cursor location in a file… somewhere… but where?

Using something like find ~ -mmin -1 I searched for where this info is stored immediately after I know it was updated. This should tell me all files changed within the last minute in my home directory but no luck - all the files changing shows no evidence of such file-unique data. I tried other directories like /var and /usr but again, no luck.

Since 16.04 seems to have dropped this feature altogether I was trying to get smarter on it. Am I doing something wrong? TIA