Title: Get MessageDlg relative to form
This example shows a creation of Message Dialog relative to center of Form1.
procedure TForm1.Button1Click(Sender: TObject);
var
MyForm: TForm;
begin
MyForm:=CreateMessageDialog('This is example', mtInformation, [mbOk]);
with MyForm do
begin
Height:=130;
Width:=150;
Left:=Trunc((Form1.Width-Width)/2)+Form1.Left;
Top:=Trunc((Form1.Height-Height)/2)+Form1.Top;;
ShowModal;
end;
end;