How to search a TRichEdit for lines with a special pattern and change their colour

Problem/Question/Abstract:

How do I scan a TRichEdit from top to bottom and check for lines with a special pattern to change color? I only know SelStart and SelLength, but how do I select a line at a time?

Answer:

var
  S: string;
  i: Integer;

{ ... }
with richedit1 do
begin
  lines.beginupdate;
  try
    for i := 0 to lines.count - 1 do
    begin
      S := Lines[i];
      if LineShouldBeColored(S) then
      begin
        SelStart := Perform(EM_LINEINDEX, i, 0);
        SelLength := Length(S);
        SelAttributes.Color := clRed;
      end;
    end;
  finally
    SelStart := 0;
    Perform(EM_SCROLLCARET, 0, 0);
    lines.endupdate;
  end;
end;