[dec]

Hola,

Esto parece funcionar estupendamente:

Código Delphi [-]
unit Unit1;
 
 interface
 
 uses
   Windows, Forms, Messages;
 
 type
   TForm1 = class(TForm)
   protected
     procedure WndProc(var Message: TMessage); override;
   end;
 
 var
   Form1: TForm1;
 
 implementation
 
 {$R *.dfm}
 
 procedure TForm1.WndProc(var Message: TMessage);
 begin
   if Message.Msg = WM_SYSCOMMAND then
   begin
     if (Message.WParam and $FFF0) = SC_MOVE then
       Message.Result := 0
     else
       inherited;
   end
   else
     inherited;
 end;
 
 end.