// get the last currently visible line
//
// this function is unsafe as it returns (size_t)-1 (i.e. a huge positive
// number) if the control is empty, use GetVisibleRowsEnd() instead, this
// one is kept for backwards compatibility
// get the last currently visible line
//
// this function is unsafe as it returns (size_t)-1 (i.e. a huge positive
// number) if the control is empty, use GetVisibleRowsEnd() instead, this
// one is kept for backwards compatibility