所要用到的函数、常量、类型 
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function WindowFromPoint Lib "user32" (ByVal x As Long, ByVal y As Long) As Long
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long

Private Const WM_GETTEXT = &HD
Private Const WM_SETTEXT = &HC


Private Type POINTAPI
x As Long
y As Long
End Type


Private Sub Form_Load()

End Sub

Private Sub Timer1_Timer()
＇
＇ 代码就是这么简单，你好好研究一下吧。
＇
＇

Dim Shu As POINTAPI
Dim Str As String * 300

GetCursorPos Shu
SendMessage WindowFromPoint(Shu.x, Shu.y), WM_GETTEXT, 299, ByVal Str
Label1.Caption = Str

End Sub 

　　根据代码加入相应控件，timer1的interval的属性为100再加入把当前窗口置顶就是一个完美的简单的取词工具了！