Question

I am trying to set the tool tip text for some of my subitems in my listview control. I am unable to get the tool tip to show up.

Anyone have any suggestions?

Private _timer As Timer
Private Sub Timer()
    If _timer Is Nothing Then
        _timer = New Timer
        _timer.Interval = 500
        AddHandler _timer.Tick, AddressOf TimerTick
        _timer.Start()
    End If
End Sub
Private Sub TimerTick(ByVal sender As Object, ByVal e As EventArgs)
    _timer.Enabled = False
End Sub

Protected Overrides Sub OnMouseMove(ByVal e As System.Windows.Forms.MouseEventArgs)
    If Not _timer.Enabled Then
        Dim item = Me.HitTest(e.X, e.Y)
        If Not item Is Nothing AndAlso Not item.SubItem Is Nothing Then
            If item.SubItem.Text = "" Then
                Dim tip = New ToolTip
                Dim p = item.SubItem.Bounds
                tip.ToolTipTitle = "Status"
                tip.ShowAlways = True
                tip.Show("FOO", Me, e.X, e.Y, 1000)
                _timer.Enabled = True
            End If
        End If
    End If

    MyBase.OnMouseMove(e)
End Sub

Answer 1

ObjectListView (an open source wrapper around .NET WinForms ListView) has builtin support for cell tooltips (and, yes, it does work with VB). You listen for a CellToolTip event and you can do things like this (which is admittedly excessive):

If you don’t want to use ObjectListView, you need to subclass ListView, listen for WM_NOTIFY messages, and then within those, respond to TTN_GETDISPINFO notifications, in a manner similar to this:

case TTN_GETDISPINFO:
    ListViewHitTestInfo info = this.HitTest(this.PointToClient(Cursor.Position));
    if (info.Item != null && info.SubItem != null) {
        // Call some method of your own to get the tooltip you want
        String tip = this.GetCellToolTip(info.Item, info.SubItem); 
        if (!String.IsNullOrEmpty(tip)) {
            NativeMethods.TOOLTIPTEXT ttt = (NativeMethods.TOOLTIPTEXT)m.GetLParam(typeof(NativeMethods.TOOLTIPTEXT));
            ttt.lpszText = tip;
            if (this.RightToLeft == RightToLeft.Yes)
                ttt.uFlags |= 4;
            Marshal.StructureToPtr(ttt, m.LParam, false);
            return; // do not do normal processing
        }
    }
    break;

Obviously, this is C#, not VB, but you get the idea.