Clear Method (NavigationBarPreviousLocationsCollection)

using System;
using System.Drawing;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using Infragistics.Shared;
using Infragistics.Win;
using Infragistics.Win.Misc;
using Infragistics.Win.Misc.UltraWinNavigationBar;

    //  Handles the form's 'Load' event.
    private void Form1_Load(object sender, EventArgs e)
    {
        //  Populate the NavigationBar and Tree from the local machine's file system
        FileSystemSupport fss = new FileSystemSupport( this.ultraNavigationBar1, this.ultraTree1 );
        fss.Populate();

        //  If this is the first time the application is being run, initialize
        //  the PreviousLocations collection by populating it from the special
        //  system folders. If this is not the first time the application is
        //  being run, load the previous locations from a file.
        if ( this.runOnce )
            this.InitializePreviousLocations( this.ultraNavigationBar1 );
        else
        {
            string folderPath = System.Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
            string filePath = String.Format(@"{0}\{1}.xml", folderPath, "PreviousLocations");
            if ( System.IO.File.Exists(filePath) )
                this.ultraNavigationBar1.PreviousLocations.LoadFromXml(filePath);
        }

        //  Register as a listener of the PreviousLocationsDropDownButtonToolTipDisplaying event.
        this.ultraNavigationBar1.PreviousLocationsDropDownButtonToolTipDisplaying += new ToolTipDisplayingHandler(this.OnPreviousLocationsDropDownButtonToolTipDisplaying);
    }

    //  Handles the form's 'Closing' event.
    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        int count = this.ultraNavigationBar1.PreviousLocations.Count;
        int rootCount = this.ultraNavigationBar1.RootLocation.Locations.Count;

        string folderPath = System.Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
        string filePath = String.Format(@"{0}\{1}.xml", folderPath, "PreviousLocations");
        this.ultraNavigationBar1.PreviousLocations.SaveAsXml(filePath);
    }

    //  Populates the specified UltraNavigationBar's PreviousLocations collection
    //  from the local machine's special system folders.
    private void InitializePreviousLocations( UltraNavigationBar navigationBar )
    {
        if ( navigationBar == null )
            throw new ArgumentNullException("navigationBar");

        //  Clear the current contents of the collection.
        navigationBar.PreviousLocations.Clear();

        //  Set the tooltip text for the dropdown button to something
        //  a little more descriptive than the default.
        navigationBar.PreviousLocationsSettings.DropDownButtonToolTipText = "Click to show most recently visited locations";

        //  Restrict the number of items that can exist in the collection to 50.
        navigationBar.PreviousLocationsSettings.MaximumItems = 50;

        //  Pre-populate the collection with some of the most commonly used
        //  directories to provide "shortcuts" for the end user.
        string pathSeparator = navigationBar.PathSeparator;
        Array values = Enum.GetValues( typeof(Environment.SpecialFolder) );
        NavigationBarPreviousLocationsCollection previousLocations = navigationBar.PreviousLocations;

        for ( int i = 0; i < values.Length; i ++ )
        {
            string folderPath = System.Environment.GetFolderPath( (Environment.SpecialFolder)values.GetValue(i) );
            folderPath = folderPath.Replace( @"\", pathSeparator );
            UltraNavigationBarLocation location = navigationBar.FromFullPath( folderPath );
            if ( location != null && previousLocations.Contains(location) == false )
                previousLocations.Add( location );
        }

        //  Set the MaximumDropDownItems property to the same value as the
        //  inital number of members in the collection.
        navigationBar.PreviousLocationsSettings.MaximumDropDownItems = previousLocations.Count;
    }

    //  Handles the UltraNavigationBar's PreviousLocationsDropDownButtonToolTipDisplaying event.
    private void OnPreviousLocationsDropDownButtonToolTipDisplaying(object sender, ToolTipDisplayingEventArgs e)
    {
        UltraNavigationBar navigationBar = sender as UltraNavigationBar;
        NavigationBarPreviousLocationsCollection previousLocations = navigationBar.PreviousLocations;

        //  If the PreviousLocations collection is not empty, display the
        //  full path for the first 5 members in the tooltip text.
        if ( previousLocations.Count > 0 )
        {
            StringBuilder sb = new StringBuilder();
            sb.Append( string.Format("Shortcuts:{0}", Environment.NewLine) );

            int count = Math.Min(previousLocations.Count, 5);
            for ( int i = 0; i < count; i ++ )
            {
                sb.Append( previousLocations[i].GetFullPath(FullPathFormat.EditMode) );

                //  Append a new line if this is not the last iteration of the loop;
                //  if it is the last iteration, and the collection count is greater
                //  than what we are showing here, append an ellipsis.
                if ( i < (count - 1) )
                    sb.Append(Environment.NewLine);
                else
                {
                    if ( previousLocations.Count > count )
                        sb.Append( "..." );
                }
            }

            //  Assign the string we just built to the ToolTipText property
            //  of the event arguments...this will override the value of the
            //  DropDownButtonToolTipText property (of the control's
            //  PreviousLocationsSettings), so that this string will be displayed
            //  instead.
            e.ToolTipText = sb.ToString();
        }
    }