Some ways this could be extended:

• Click midpoint between two key points to insert a new key point.
• Click on a key point to delete it.
• Toggle between open and closed curve.
• Toggle curve appearance: stroke or fill or both in different colors.
• Toggle key points between visible and invisible.
• Support multiple curves.
• Use multiple bsplines to create your own font.
• Build a font designer.
• Use multiple bsplines to make an animated face.