Dialog pops up when double clicking in playlist

[wtfwtfwtfwtf]

All of a sudden, I am getting a dialog box when I double click an item in the playlist.

This never happened before.

I am using 5.61 x86. Registered pro version.

The dialog says "Add files to playlist."

This is new behavior. How do I turn it off?

I am not using any extra plugins or anything.

Thank you