You can surely fork it on github.
I wrote this extension for myself and I don't need any more functionality. But if someone wants a thing or two, I will try to implement it. But at the moment there's no interest from the user base, so I'm not willing to code new features.
It would be good to be able to configure it more. For example, to show that properties box only if user is holding Ctrl or something like that. Or to show the box near the cursor, and not in the corner.