protected void DisposeBrushes()
{
if (m_brushSurface != null) {
m_brushSurface.Dispose();
m_brushSurface = null;
}
if (m_brushStartSide != null) {
m_brushStartSide.Dispose();
m_brushStartSide = null;
}
if (m_brushEndSide != null) {
m_brushEndSide.Dispose();
m_brushEndSide = null;
}
if (m_brushPeripherySurface != null) {
m_brushPeripherySurface.Dispose();
m_brushPeripherySurface = null;
}
}