C# ListView mouse wheel scroll without focus

Question

I'm making a WinForms app with a ListView set to detail so that several columns can be displayed.

I'd like for this list to scroll when the mouse is over the control and the user uses the mouse scroll wheel. Right now, scrolling only happens when the ListView has focus.

How can I make the ListView scroll even when it doesn't have focus?

Answer 1

You'll normally only get mouse/keyboard events to a window or control when it has focus. If you want to see them without focus then you're going to have to put in place a lower-level hook.

Here is an example low level mouse hook

Answer 2

"Simple" and working solution:

public class FormContainingListView : Form, IMessageFilter
{
    public FormContainingListView()
    {
        // ...
        Application.AddMessageFilter(this);
    }

    #region mouse wheel without focus

    // P/Invoke declarations
    [DllImport("user32.dll")]
    private static extern IntPtr WindowFromPoint(Point pt);
    [DllImport("user32.dll")]
    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

    public bool PreFilterMessage(ref Message m)
    {
        if (m.Msg == 0x20a)
        {
            // WM_MOUSEWHEEL, find the control at screen position m.LParam
            Point pos = new Point(m.LParam.ToInt32() & 0xffff, m.LParam.ToInt32() >> 16);
            IntPtr hWnd = WindowFromPoint(pos);
            if (hWnd != IntPtr.Zero && hWnd != m.HWnd && System.Windows.Forms.Control.FromHandle(hWnd) != null)
            {
                SendMessage(hWnd, m.Msg, m.WParam, m.LParam);
                return true;
            }
        }
        return false;
    }

    #endregion
}