Motion seconded. I'd love to see this be a feature for simple objects!
It would be fantastic to manipulate the border width of standard balsamiq objects like rectangles. I'm trying to mimic the minimize, maximize, and close window controls for a windows app. It doesn't look right when it's more than 1-2 pixels. Was hoping not to import a screenshot for simple shapes like two overlapping rectangles.
Your software is fantastic. Please keep up the good work!