List getSelectedValue how to setup custom parameter?

Hello,

I have two list boxes Line and Model. Model is depending from what i have selected in Line list.

After these selections I would like to get both selected values and add in to table.
I have added this code in to mouse click: value = event.source.getSelectedValue()
I can print these values in to console but I have no idea how to assign this value in to button and then add in to table. I was thinking to create custom properties for each list but I am getting error: when adding this: event.source.getSelectedValue().

I hope somebody will be able to help me with this.

All help much appreciated.

Regards
Pawel

Ok, I have figured this out.