protected void FilterLines()
{
String shown = "";
int maxLines = this.HeightInLines;
int newStart = (int)( this.scrollPercentage * ( this.lines.Count - maxLines ) + 0.5f );
this.startingLine = newStart;
for ( int i = 0; i < maxLines; i++ )
{
shown += this.lines[ this.startingLine + i ] + "\n";
}
this.textArea.Text = shown; // show just the filtered lines
}