Postmessage参数搞不懂解决方法

Postmessage参数搞不懂
请问如何在Postmessage的参数写入，屏幕的绝对坐标。对这个参数实在搞不懂，谁能帮忙给点vb的代码，谢谢了。

[解决办法]

VB code

Private Declare Function WindowFromPoint Lib "user32" (ByVal xPoint As Long, ByVal yPoint As Long) As LongPrivate Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As LongPrivate Const WM_RBUTTONDOWN = &H204Private Const WM_RBUTTONUP = &H205Private Sub Command1_Click()    PThwnd = WindowFromPoint(100, 100)    PostMessage PThwnd, WM_RBUTTONDOWN, 0, 0    PostMessage PThwnd, WM_RBUTTONUP, 0, 0End Sub