Hello everyone!
In VB6 PictureBox has property "DrawMode". I could set "DrawMode" property to "Xor Pen" and draw line on the other one without deleting that line. It was useful to use in "Painting" programs. But in VB.Net there is no "DrawMode" property, but it is written in MSDN that the property was replaced with "Pen.Color". But I can't use "Pen.Color" as "Xor".