Свертка\развертка формы, как в окошке процесса копирования win 7-8

class TForm1 : public TForm
{
__published: // IDE-managed Components
    TPanel *pnl_info1;
    TPanel *pnl_info2;
    TPanel *pnl_bottom;
    TButton *btn_roll;
    TTimer *tmr_roll_ani;
    void __fastcall btn_rollClick(TObject *Sender);
    void __fastcall tmr_roll_aniTimer(TObject *Sender);
 
public: // User declarations
 
    int min_height, max_height, direction;
    __fastcall TForm1( TComponent * Owner );
    // __fastcall ~TForm1( );
} ;

__fastcall TForm1::TForm1( TComponent * Owner ) :
    TForm( Owner )
{
    min_height = pnl_info1->BoundsRect.Bottom + pnl_bottom->Height;
    max_height = pnl_info2->BoundsRect.Bottom + pnl_bottom->Height;
    ClientHeight = max_height;
    direction = 1;
    tmr_roll_ani->Interval = 50;
}
 
// ---------------------------------------------------------------------------
void __fastcall TForm1::btn_rollClick( TObject * Sender )
{
    direction *= -1;
    tmr_roll_ani->Enabled = true;
}
// ---------------------------------------------------------------------------
 
void __fastcall TForm1::tmr_roll_aniTimer( TObject * Sender )
{
    float dif( max_height - min_height ),
        step( ceil( ( ( dif / 2 + 10 ) - fabs( dif / 2 + min_height - ClientHeight ) ) / ( dif / 50 ) ) * direction );
    TTimer * tmr( static_cast < TTimer * > ( Sender ) );
 
    ClientHeight += step;
 
    if ( ( ClientHeight < min_height ) || ( ClientHeight > max_height ) )
    {
        if ( direction < 0 )
        {
            ClientHeight = min_height;
        }
        else
        {
            ClientHeight = max_height;
        }
        tmr->Enabled = false;
    }
}