How to add my own module widget to another module?

[drobny (David)]

Here seems to be a related issue with the Markups module:

Would it be possible to have more then one module panel?

Actually, while this popups up the module, the module itself is not functional. I am trying particularly with the Markups module, and you can’t see the control points, nor modify their color/size etc with the popup Markups module, while the docked one in the main module panel works fine.