Question

So I have a TreeView in a C# windows form app. What I need is for some nodes to be “locked” so that they cannot be checked (or unchecked), based on a parameter.

What I am doing now is this:

private void tv_local_BeforeCheck(object sender, TreeViewCancelEventArgs e) {
    TNode node = (TNode)e.Node;
    //if a part node, cancel the action.
    if (node.Type == "Part") {
        e.Cancel = true;     
    }
    //if a locked node, cancel the action
    if (node.Locked == true) {
        e.Cancel = true;
    }
}

This code works great on a single click of the checkbox, but if the user double clicks on a checkbox, it still checks/unchecks.

I have tried playing with the nodeMouseDoubleClick event, but that doesnt really help, since I cannot cancel the event…

Is there any ideas out there how to cancel a double click event on a node?… or anything else?
Thanks

Answer 1

This is a bug in the TreeView I think (http://social.msdn.microsoft.com/Forums/en-US/winforms/thread/9d717ce0-ec6b-4758-a357-6bb55591f956/). You need to subclass the tree view and disable the double-click message in order to fix it. Like this:

public class NoClickTree : TreeView
    {
        protected override void WndProc(ref Message m)
        {
            // Suppress WM_LBUTTONDBLCLK
            if (m.Msg == 0x203) { m.Result = IntPtr.Zero; }
            else base.WndProc(ref m);
        }              
    };

Of course if you do this you’ll no longer be able to use the double-click metaphor in the tree-view for other things (such as double click a node to launch a property page, or something).