StartTop Property
Used in conjunction with the EndTop, EndLeft and StartLeft properties to define the path and extent of the brush evaluation. StartTop is a percentage.
A Brush defined as StartLeft(0) StartTop(0) EndLeft(100) EndTop(100) will appear to travel diagonally from the top left to the bottom right.
A Brush defined as StartLeft(0) StartTop(0) EndLeft(0) EndTop(100) will appear to travel vertically from the top to the bottom.
A Brush defined as StartLeft(0) StartTop(0) EndLeft(0) EndTop(50) will appear to travel vertically from the top to half way down the control. The Spread property will determine appearance beyond the extent of the start and end coordinates.