#Region "搜索框的全选"
Dim counter As Integer = 0 '点击次数
Dim isSelectAll As Boolean = False '是否全选
Dim selectPoint As Integer = 0 '当前光标位置
Private Sub TextBox1_Click(ByVal sender As Object,ByVal e As System.EventArgs) Handles TextBox1.Click
counter += 1
If counter = 1 Then '判断是否首次点击
selectPoint = TextBox1.SelectionStart
TextBox1.SelectAll()
isSelectAll = True
ElseIf counter > 1 Then
If TextBox1.SelectionLength = 0 Then '判断选择字符的长度是否为0
If TextBox1.SelectionStart = selectPoint Then '判断是否点击上次同一位置
If isSelectAll = True Then
isSelectAll = False
Else
TextBox1.SelectAll()
isSelectAll = True
End If
Else
If TextBox1.SelectionStart = TextBox1.TextLength AndAlso isSelectAll = False Then '判断光标位置在最末
TextBox1.SelectAll()
isSelectAll = True
Else
selectPoint = TextBox1.SelectionStart '不是上次同一位置，则记录当前位置
isSelectAll = False
End If
End If
End If
End If
End Sub
Private Sub TextBox1_LostFocus(ByVal sender As Object,ByVal e As System.EventArgs) Handles TextBox1.LostFocus
counter = 0
End Sub
Private Sub TextBox1_DoubleClick(ByVal sender As Object,ByVal e As System.EventArgs) Handles TextBox1.DoubleClick
isSelectAll = True
End Sub
#End Region