Changing the properties of all components of a certain type

To change the font color of all the labels of a form to the same color, call the following procedure. In the call, you have to replace NewColor with an existing color, e.g. SetLabelsFontColor(clRed) sets all the labels' font color to red:

procedure TForm1.SetLabelsFontColor(NewColor: TColor);
var
  i: Integer;
begin
  for i := 0 to ComponentCount - 1 do
    if Components[i] is TLabel then
      TLabel(Components[i]).Font.Color := NewColor;
end;

Of course, you can use this technique to change other properties of other components. To change the color of all the edit components, use the following code:

procedure TForm1.SetEditsColor(NewColor: TColor);
var
  i: Integer;
begin
  for i := 0 to ComponentCount - 1 do
    if Components[i] is TEdit then
      TEdit(Components[i]).Color := NewColor;
end;