You did not post your Block image so I do not really know how you are drawing. Probably instead of Canvas1.DrawLine in your Canvas1.Dragged event handler, use Canvas1.DrawCircle which will draw a smoother, wide line.

1) line / is a continuous line with width of 2 using DrawLine
2) line / is a continuous line with width of 10 using DrawLine ... what you show
3) circle 0 is a continuous line drawn with width of 2 using DrawCircle
4) circle 0 is a continuous line drawn with width of 10 using DrawCircle
Did it work for you?
Regards,
Steve