form1.repaint;    
form1.Canvas.pen.color:=clGreen;    
form1.Canvas.pen.width:=5;    
form1.Canvas.polyline([point(Button1.left,Button1.top),    
point(Button1.left+Button1.width,Button1.top),    
point(Button1.left+Button1.width,Button1.top+Button1.hei    
ght),    
point(Button1.left,Button1.top+Button1.height),    
point(Button1.left,Button1.top)]);    
end;    
   
procedure TForm1.Button2MouseMove    
(Sender:TObject;Shift:TShiftState;X,    
Y:Integer);    
begin    
form1.repaint;    
form1.Canvas.pen.color:=clBlue;    
form1.Canvas.pen.width:=5;    
form1.Canvas.polyline([point(Button2.left,Button2.top),    
point(Button2.left+Button2.width,Button2.top),    
point(Button2.left+Button2.width,Button2.top+Button2.hei    
ght),    
point(Button2.left,Button2.top+Button2.height),    
point(Button2.left,Button2.top)]);    
end;    
   
procedure TForm1.FormMouseMove    
(Sender:TObject;Shift:TShiftState;X,    
Y:Integer);    
begin    
form1.repaint;    
form1.Canvas.pen.color:=clRed;    
form1.Canvas.pen.width:=3;    
form1.Canvas.polyline([point(0,0),point(form1.width-    
10,0),    
point(form1.width-10,form1.height-30),    
point(0,form1.height-30),point(0,0)]);    
end;    
   
   
   
3.为图形按钮或其它控件安装动态帮助功能,此处主要使用它的    
字符串显示功能,也就是当鼠标移到指定控件上时,在其周围适当    
位置显示相应的字符串,当鼠标离开时通过图像覆盖动作使字符    
串消失,也可以使用一个简单的命令完成即form1.repaint,它的    
作用是使FORM1内的所有控件全部重新绘制,这样即可快速清除    
原来显示的字符;编程时主要使用各个控件的MouseMove()事件;    
比如可在窗口中安放两个按钮,并安排如下代码,运行之后当鼠标    
移到相应按钮上时,就会在其上方显示相应的提示信息,鼠标移到    
窗口空白处则会在窗口的左下角显示"OK"字样;    
   
   
procedure TForm1.Button1MouseMove    
(Sender:TObject;Shift:TShiftState;X,Y:Integer);    
begin    
form1.repaint;    
form1.Canvas.brush.color:=clGreen;    
form1.Canvas.font.size:=8; &nbs