Why does System.Windows.Controls.Button always have a padding of 10px?

Question

See screenshot. The bounding cyan-bordered box is the button, while the blue fill is the rectangle. I cannot for the life of me figure out how to get rid of the padding in the b

Answer 1

Did you try setting the Rectangle's margin to 0?

EDIT: The padding must come from the button control template. Try using a custom template: