Preview of Preview Dialog features.

[micheus]

I believe just one for all plugins would avoid to mess up the wings3d' file as well as avoid corrupt it. But, I'm not sure about how much hard/easy could be to manage it. The information/s of the window/s plugin is/are stored into the currente preference file.
Your idea about to store blocks in such a file - if used only for extra plugin data - sounds better.