...make a form not resizable but moveable?

private
   procedure WMGetMinMaxInfo(var Msg: TWMGetMinMaxInfo); message WM_GETMINMAXINFO;
end;

{...}

implementation

procedure TForm1.WMGetMinMaxInfo(var Msg: TWMGetMinMaxInfo);
begin
  inherited;
  with Msg.MinMaxInfo^ do 
  begin
    ptMinTrackSize.x := Form1.Width;
    ptMaxTrackSize.x := Form1.Width;
    ptMinTrackSize.y := Form1.Height;
    ptMaxTrackSize.y := Form1.Height;
  end;
end;