一個窗體特效，幫你了解幾個windows api函數.效果：windows桌面上增加一個簡單的遮罩層,其中WS_EX_TRANSPARENT 比較重要，它實現了鼠標穿透的功能。

1. usingSystem;
3. usingSystem.Drawing;
5. usingSystem.Windows.Forms;
7. usingSystem.Runtime.InteropServices;
9. namespaceWindowsapplication40
11. {
13. publicpartialclassForm1:Form
15. {
17. publicForm1()
19. {
21. InitializeComponent();
23. }
25. [DllImport("user32.dll",EntryPoint="GetWindowLong")]
27. publicstaticexternlongGetWindowLong(IntPtrhwnd,intnIndex);
31. [DllImport("user32.dll",EntryPoint="SetWindowLong")]
33. publicstaticexternlongSetWindowLong(IntPtrhwnd,intnIndex,longdwNewLong);
37. [DllImport("user32",EntryPoint="SetLayeredWindowAttributes")]
39. PRivatestaticexternintSetLayeredWindowAttributes(IntPtrHandle,intcrKey,bytebAlpha,intdwFlags);
43. constintGWL_EXSTYLE=-20;
45. constintWS_EX_TRANSPARENT=0x20;
47. constintWS_EX_LAYERED=0x80000;
49. constintLWA_ALPHA=2;
55. privatevoidForm1_Load(objectsender,EventArgse)
57. {
59. this.BackColor=Color.Silver;
61. this.TopMost=true;
63. this.FormBorderStyle=FormBorderStyle.None;
65. this.WindowState=FormWindowState.Maximized;
67. SetWindowLong(Handle,GWL_EXSTYLE,GetWindowLong(Handle,GWL_EXSTYLE)|WS_EX_TRANSPARENT|WS_EX_LAYERED);
69. SetLayeredWindowAttributes(Handle,0,128,LWA_ALPHA);
73. }
75. }
77. }