Requirements:
- Drawing of a line with two control points (first diameter)
- Optional: drawing of a second line with two control points which satisfy the following conditions:
- Second line is orthogonal to first line
- Second line must intersect first line
- When the first line has been drawn, an infinite transparent line shall be drawn at the position of the mouse to indicate at which position the second line would be put when setting its control points
- The infinite transparent helper line shall satisfy the same requirements indicated above