一个例子<br>procedure TForm1.FormClick(Sender: TObject);<br>var<br> R : HRgn;<br>begin<br> if IsRound then<br> begin<br> SetWindowRgn(Handle,0,True);<br> DeleteObject(R);<br> IsRound := False;<br> end<br> else<br> begin<br> R := CreateEllipticRgn(-15,-15,Width+15,Height+15);<br> SetWindowRgn(Handle,R,True);<br> IsRound := True;<br> end;<br>end;<br><br>procedure TForm1.FormCreate(Sender: TObject);<br><br>begin<br> IsRound := False;<br>end;<br><br>end.<br><br>