TextBoxGetLineColumn - Get caret position in a multiline TextBox control

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
Const EM_LINEFROMCHAR = &HC9
Const EM_LINEINDEX = &HBB

' Get the line/column coordinates of a given character (both are zero-based).
' If charIndex is negative, it returns the coordinates of the caret

Sub TextBoxGetLineColumn(tb As TextBox, ByVal charIndex As Long, line As Long, _
    column As Long)
    If charIndex < 0 Then charIndex = tb.SelStart
    ' Get the line number.
    line = SendMessage(tb.hwnd, EM_LINEFROMCHAR, charIndex, ByVal 0&)
    ' Get the column number by subtracting the line's start
    ' index from the caret position
    column = tb.SelStart - SendMessage(tb.hwnd, EM_LINEINDEX, line, ByVal 0&)
End Sub