VB - What listbox item is the mouse over

[MerrionComputin]

Useful for providing context feedback etc.

'\\ API declarations
Const LB_GETITEMHEIGHT = &H1A1
Const LB_GETTOPINDEX = &H18E
 
Private Declare Function SendMessageByValLong Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
Private Function ListIndexAtPosition(ByVal YPos As Single, lstFields As ListBox) As Long
    Dim lItemHeight As Long 'height of an entry In the listbox in pixels..
    Dim lTopIndex As Long
    Dim lEntry As Long
    Dim nYpos As Integer
    
    On Error Resume Next
    '\\ 1 - Get the height of each item...
    lItemHeight = SendMessageByValLong(lstFields.hWnd, LB_GETITEMHEIGHT, 0, 0)
    lItemHeight = lItemHeight * Screen.TwipsPerPixelY
    '\\ 2 - Get index of the topmost item...
    lTopIndex = SendMessageByValLong(lstFields.hWnd, LB_GETTOPINDEX, 0, 0)
 
    '\\ Find the Y position in pixels
    lEntry = lTopIndex + (YPos \ lItemHeight)
    ListIndexAtPosition = lEntry
    
End Function

Example of use...

Private Sub List1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
 
Label1.Caption = "Over index " & ListIndexAtPosition(Y, List1)
 
End Sub