代码如下
Option Explicit
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Integer, ByVal lParam As Any) As Long
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Const WM_LBUTTONDOWN = &H201
Const WM_LBUTTONUP = &H202
Dim H As Long
Private Sub Form_DblClick()
Sleep 300
H = Text1.Text
SendMessage H, WM_LBUTTONDOWN, 0, 0&
SendMessage H, WM_LBUTTONUP, 0, 0&
End Sub
Private Sub Text1_Click()
Text1.Text = ""
End Sub

反正就是和其他代码冲突了，不能添加 ByVal 这个单词，有没有大神帮我抢救下 0.0

你声明H应该是来存储句柄的，所以H = text1.hWnd

另外，wParam也应该为Long型吧

你把declare里的byval 删了，用调用时加byval就行了，这里要注意，只能是any不然会提示类型不对

看到了没有，这里wParam是一个long长整型，你抄了多少年前的代码？