unit Msg;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs;

type
  TForm1 = class(TForm)
  private
    { Private declarations }
    procedure WMGetMinMaxInfo(var MSG: Tmessage); message WM_GetMinMaxInfo;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMGetMinMaxInfo(var MSG: Tmessage);
Begin
  inherited;
  with PMinMaxInfo(MSG.lparam)^ do
  begin
    with ptMinTrackSize do
    begin
      X := 300;
      Y := 150;
    end;
    with ptMaxTrackSize do
    begin
      X := 350;
      Y := 250;
    end;
  end;
end;

end.