animate the position of the button according to the scrolling inside datagrid!

I've found

VisibleRowsCount = (BitmapLister.table.Height-24)/30

intRows = dataGridView1.Rows.GetRowCount(DataGridViewElementStates.Displayed);
intBottom = intRows + intTop - 1;

BitmapLister.table.Rows.GetRowCount(DataGridViewElementStates.Displayed)

is giving error also

on table Scroll ScrollChangedEventArgs e do
(
 
	print table.FirstDisplayedScrollingRowIndex	
 
)

works but there is no LastDisplayedScrollingRowIndex

I thought to use http://msdn.microsoft.com/en-us/library/system.windows.forms.datagrid.vi…

print BitmapLister.table.VisibleRowCount

but it gives error!

PLEASE HELP!!!

on table Scroll ScrollChangedEventArgs e do
(

	print first visible row index
	print last visible row index	

)

--on table SelectionChanged senderArg arg do

on table Scroll ScrollViewer.ScrollChanged ScrollChangedEventArgs

private void cbdg1_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
double d = e.VerticalOffset;

// Here you can use the vertical-offset's value.
}

http://msdn.microsoft.com/en-us/library/system.windows.forms.datagrid.vi…

http://stackoverflow.com/questions/658258/wpf-datagrid-check-visible-row…

http://stackoverflow.com/questions/5979827/count-the-number-of-visible-r…

http://asifhuddani.wordpress.com/2010/05/24/displayedrowcount-of-datagri…

http://bytes.com/topic/c-sharp/answers/580313-determine-visible-row-winf…

Look! Let, say, I have the line order, and 30 px for every line!
I just need a callback which detects that datagrid is scrolling items! and during this scrolling we need to detect just which lines are visible! Everything else I will try by myself!

tell me please at least where to search?
The height of a row is 30px! may be to detect smth like which line is visible!