Code:

constructor TMainForm.Create(AOwner: TComponent);

begin

Inherited Create(AOwner);

SetWindowLong(ClientHandle, GWL_EXSTYLE,

GetWindowLong(ClientHandle,

GWL_EXSTYLE) or WS_EX_CLIENTEDGE);

SetWindowPos(ClientHandle, 0, 0, 0, 0, 0,

   swp_DrawFrame or swp_NoMove or swp_NoSize

   or swp_NoZOrder);

end;