At the moment I’m working on an Intranet that has to comply completely to the Dutch ‘webrules’ (Webrichtlijnen - http://www.webrichtlijnen.nl/).
One part of this is that the navigation has to be a ‘<ul><li>’- structure instead of the standard SharePoint table-structure.
Therefore we adjusted the rendering of the topnavigation so now neat XHTML is rendered.

The challenge is to make this menu, which is a foldout-menu, compliant to IE6 and IE7.
The folding uses the following css-code for hiding and revealing:

div#menu ul ul ul, div#menu ul ul li:hover ul ul {display: none;}
div#menu ul ul li:hover ul, div#menu ul ul ul li:hover ul {display: block;}

However a hover on a li-element doesn’t function in IE6 en IE7.
The solution is to make use of the following HTC-file:
http://www.xs4all.nl/~peterned/csshover.html#changes.
This file is referenced from out the CSS:
body{ behavior: url("../includes/csshover.htc");}

The result is a browsercompliant accessible foldout topnavigation that uses the standard SharePoint SiteMapDataSource.

Meer informatie op http://www.mavention.nl/SharePoint2010

Allot of controls found in Microsoft.SharePoint.WebControls can be used in custum code. Some of these controls get their values from the current SPContext. If you use for instance the ListFieldIterator to show the metadata from a listitem on another web you will get errors because it's using the wrong context. This can be fixed by using SPControl.SetContextWeb() but be awar that this will change the entire conext of the page. It will show your page but the menu and site actions think you are on the web of the listitem. There's no prefect solution for fixing this but one approach is to create an applicationpage and set the context using SPControl.SetContextWeb and load this in a pop-up or iframe.

Lately a customer of mine had specific demands regarding their portal site. They wanted menu items containing sub menu items to be unclickable. Now this is not standard SharePoint menu behavior, so I Bang some about this. (Is Bang past tense for Bing?).

Anyways, there is a lot to find about overriding the menu control. Especially Microsoft (http://blogs.msdn.com/sharepoint/archive/2006/12/02/customizing-the-wss-3-0-moss-2007-menu-control.aspx) has some clear explanation on how to do this.

In short: you cannot override the MOSS menu control class because it is sealed. Therefore Microsoft has provided us with source code that can be used for this goal. This class you can override or tweak.

As I mentioned some menu items had to be "unclickable". This I achieved by doing the following:
 
First I added a method:
        private void DisableParentMenuItems(MenuItem menuItem)
        {
            // No kids. Keep this one selectable
            if (menuItem.ChildItems.Count == 0)
                return;
            // Kids. Process them
            foreach (MenuItem childItem in menuItem.ChildItems)
                DisableParentMenuItems(childItem);
            // Kids. This menu item may not be clickable.
            // Menu item with depth=0 is the root item and is the only one exception that should be selectable in case we use portal root site in navigation
            // which we dont here.
            if (menuItem.Depth >= 0)
                menuItem.Selectable = false;
            //menuItem.ToolTip += menuItem.Depth.ToString();
        }


After that I added code to the end of the OnPreRender method:
            // iterate through all top level menu items
            foreach (MenuItem menuItem in this.Items)
                DisableParentMenuItems(menuItem);

Make sure you use the standard procedure to have the menu control deployed (I used a solution for this), having the SafeControl added etc. The last thing to do is to modify the master page in order to use the new menu control (and don't forget the publishing of the page).