1.在Form1中加入兩個CommandButton和一個PictureBox.

2.在Form1的代碼窗口中添加以下代碼：
Privatebybits(1To16)AsByte
PrivatehBitmapAsLong,hBrushAsLong
PrivatehDesktopWndAsLong

PrivateSubCommand1_Click()
DimropAsLong,resAsLong
Dimhdc5AsLong,width5AsLong,height5AsLong
hdc5=GetDC(0)
width5=Screen.Width/Screen.TwipsPerPixelX
height5=Screen.Height/Screen.TwipsPerPixelY
rop=&HA000C9
CallSelectObject(hdc5,hBrush)
res=PatBlt(hdc5,0,0,width5,height5,rop)
CallDeleteObject(hBrush)
res=ReleaseDC(0,hdc5)
EndSub

PrivateSubCommand2_Click()
DimaaAsLong
aa=InvalidateRect(0,0,1)
EndSub
PrivateSubForm_Load()
Dimary
DimiAsLong
ary=Array(&H55,&H0,&HAA,&H0,_
&H55,&H0,&HAA,&H0,_
&H55,&H0,&HAA,&H0,_
&H55,&H0,&HAA,&H0)
Fori=1To16
bybits(i)=ary(i-1)
Nexti
hBitmap=CreateBitmap(8,8,1,1,bybits(1))
hBrush=CreatePatternBrush(hBitmap)
Picture1.ForeColor=RGB(0,0,0)
Picture1.BackColor=RGB(255,255,255)
Picture1.ScaleMode=3
EndSub

運行程序，按Command1就可以使屏幕暗下來，按Command2恢復。