Выделение всей строки в TextBox

Option Explicit
 
Private Const CB_FINDSTRING = &H14C
Private Const CB_SHOWDROPDOWN = &H14F
Private Const LB_FINDSTRING = &H18F
Private Const CB_ERR = (-1)
 
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 Sub mCombo_KeyPress(KeyAscii As Integer)
 
    Dim CB As Long, b As Long
    Dim FindString As String
    
    If KeyAscii < 32 Then Exit Sub
    
    If mCombo.SelLength = 0 Then
        FindString = mCombo.Text & Chr$(KeyAscii)
    Else
        FindString = Left$(mCombo.Text, mCombo.SelStart) & Chr$(KeyAscii)
    End If
 
    CB = SendMessage(mCombo.hwnd, CB_FINDSTRING, -1, ByVal FindString)
    lblTest.Caption = vbNullString
    
    If CB <> CB_ERR Then
        Do Until (CB <= b) And b
            lblTest.Caption = lblTest.Caption & mCombo.List(CB) & vbNewLine
            b = CB
            CB = SendMessage(mCombo.hwnd, CB_FINDSTRING, b + 1, ByVal FindString)
            DoEvents
        Loop
        mCombo.ListIndex = CB
        mCombo.SelStart = Len(FindString)
        mCombo.SelLength = Len(mCombo.Text) - mCombo.SelStart
    Else
        mCombo.Text = FindString
        mCombo.SelStart = Len(FindString)
    End If
   
    KeyAscii = 0
    
End Sub