Pickbutton problems

Hey there. I have made a visual script that evenly spaces vertices of a spline when using the normalize spline modifier. you can also choose how many vertices.

My problem is that the script uses a pickbutton to pick the spline. It's not absolutely necessary to have this but it's nice if you have a dense scene.

The other problem is that the script adds modifiers or, if I want, it collapses the stack to an editable spline. If it is selected I can continually keep changing the number of verts via release of the spinner button. However, once it is unclicked, the line filter won't allow me to select it anymore because it now has modifiers or editable spline

So if I don't like the amount of verts and i've accidentally unclicked it or decided after the fact, the pickbutton doesn't work anymore. How can I have the pickbutton work on a modified object or editable spline? Can I also have 2 filters and not just one for the pickbutton?