Change the appearance of the ToolbarControl
Appearance.cs
// Copyright 2012 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

using ESRI.ArcGIS.Controls;
using ESRI.ArcGIS.SystemUI;
using ESRI.ArcGIS;

namespace Appearance
{

  public class Form1 : System.Windows.Forms.Form
  {
    internal System.Windows.Forms.CheckBox chkFillDirection;
    internal System.Windows.Forms.Button btnFadeColor;
    internal System.Windows.Forms.Button btnBackColor;
    internal System.Windows.Forms.CheckBox chkHiddenItems;
    internal System.Windows.Forms.CheckBox chkOrientation;
    private ESRI.ArcGIS.Controls.AxToolbarControl axToolbarControl1;
    private ESRI.ArcGIS.Controls.AxGlobeControl axGlobeControl1;
    private ESRI.ArcGIS.Controls.AxLicenseControl axLicenseControl1;

    private System.ComponentModel.Container components = null;

    public Form1()
    {

      InitializeComponent();

    }

    protected override void Dispose( bool disposing )
    {
            ESRI.ArcGIS.ADF.COMSupport.AOUninitialize.Shutdown();
      if( disposing )
      {
        if (components != null) 
        {
          components.Dispose();
        }
      }
      base.Dispose( disposing );
    }

    #region Windows Form Designer generated code
    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
            System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(Form1));
            this.chkFillDirection = new System.Windows.Forms.CheckBox();
            this.btnFadeColor = new System.Windows.Forms.Button();
            this.btnBackColor = new System.Windows.Forms.Button();
            this.chkHiddenItems = new System.Windows.Forms.CheckBox();
            this.chkOrientation = new System.Windows.Forms.CheckBox();
            this.axToolbarControl1 = new ESRI.ArcGIS.Controls.AxToolbarControl();
            this.axGlobeControl1 = new ESRI.ArcGIS.Controls.AxGlobeControl();
            this.axLicenseControl1 = new ESRI.ArcGIS.Controls.AxLicenseControl();
            ((System.ComponentModel.ISupportInitialize)(this.axToolbarControl1)).BeginInit();
            ((System.ComponentModel.ISupportInitialize)(this.axGlobeControl1)).BeginInit();
            ((System.ComponentModel.ISupportInitialize)(this.axLicenseControl1)).BeginInit();
            this.SuspendLayout();
            // 
            // chkFillDirection
            // 
            this.chkFillDirection.Location = new System.Drawing.Point(408, 168);
            this.chkFillDirection.Name = "chkFillDirection";
            this.chkFillDirection.Size = new System.Drawing.Size(144, 24);
            this.chkFillDirection.TabIndex = 13;
            this.chkFillDirection.Text = "Vertical Fill Direction";
            this.chkFillDirection.CheckedChanged += new System.EventHandler(this.chkFillDirection_CheckedChanged);
            // 
            // btnFadeColor
            // 
            this.btnFadeColor.Location = new System.Drawing.Point(408, 136);
            this.btnFadeColor.Name = "btnFadeColor";
            this.btnFadeColor.Size = new System.Drawing.Size(112, 23);
            this.btnFadeColor.TabIndex = 12;
            this.btnFadeColor.Text = "Fade Color";
            this.btnFadeColor.Click += new System.EventHandler(this.btnFadeColor_Click);
            // 
            // btnBackColor
            // 
            this.btnBackColor.Location = new System.Drawing.Point(408, 104);
            this.btnBackColor.Name = "btnBackColor";
            this.btnBackColor.Size = new System.Drawing.Size(112, 23);
            this.btnBackColor.TabIndex = 11;
            this.btnBackColor.Text = "Back Color";
            this.btnBackColor.Click += new System.EventHandler(this.btnBackColor_Click);
            // 
            // chkHiddenItems
            // 
            this.chkHiddenItems.Location = new System.Drawing.Point(408, 72);
            this.chkHiddenItems.Name = "chkHiddenItems";
            this.chkHiddenItems.Size = new System.Drawing.Size(152, 16);
            this.chkHiddenItems.TabIndex = 10;
            this.chkHiddenItems.Text = "Show Hidden Items";
            this.chkHiddenItems.CheckedChanged += new System.EventHandler(this.chkHiddenItems_CheckedChanged);
            // 
            // chkOrientation
            // 
            this.chkOrientation.Location = new System.Drawing.Point(408, 48);
            this.chkOrientation.Name = "chkOrientation";
            this.chkOrientation.Size = new System.Drawing.Size(152, 16);
            this.chkOrientation.TabIndex = 9;
            this.chkOrientation.Text = "Vertical Orientation";
            this.chkOrientation.CheckedChanged += new System.EventHandler(this.chkOrientation_CheckedChanged);
            // 
            // axToolbarControl1
            // 
            this.axToolbarControl1.Location = new System.Drawing.Point(8, 8);
            this.axToolbarControl1.Name = "axToolbarControl1";
            this.axToolbarControl1.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("axToolbarControl1.OcxState")));
            this.axToolbarControl1.Size = new System.Drawing.Size(490, 28);
            this.axToolbarControl1.TabIndex = 14;
            // 
            // axGlobeControl1
            // 
            this.axGlobeControl1.Location = new System.Drawing.Point(40, 40);
            this.axGlobeControl1.Name = "axGlobeControl1";
            this.axGlobeControl1.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("axGlobeControl1.OcxState")));
            this.axGlobeControl1.Size = new System.Drawing.Size(362, 391);
            this.axGlobeControl1.TabIndex = 15;
            // 
            // axLicenseControl1
            // 
            this.axLicenseControl1.Enabled = true;
            this.axLicenseControl1.Location = new System.Drawing.Point(408, 399);
            this.axLicenseControl1.Name = "axLicenseControl1";
            this.axLicenseControl1.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("axLicenseControl1.OcxState")));
            this.axLicenseControl1.Size = new System.Drawing.Size(32, 32);
            this.axLicenseControl1.TabIndex = 16;
            // 
            // Form1
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(536, 443);
            this.Controls.Add(this.axLicenseControl1);
            this.Controls.Add(this.axGlobeControl1);
            this.Controls.Add(this.axToolbarControl1);
            this.Controls.Add(this.chkFillDirection);
            this.Controls.Add(this.btnFadeColor);
            this.Controls.Add(this.btnBackColor);
            this.Controls.Add(this.chkHiddenItems);
            this.Controls.Add(this.chkOrientation);
            this.Name = "Form1";
            this.Text = "Appearance";
            this.Load += new System.EventHandler(this.Form1_Load);
            ((System.ComponentModel.ISupportInitialize)(this.axToolbarControl1)).EndInit();
            ((System.ComponentModel.ISupportInitialize)(this.axGlobeControl1)).EndInit();
            ((System.ComponentModel.ISupportInitialize)(this.axLicenseControl1)).EndInit();
            this.ResumeLayout(false);

    }
    #endregion


        [STAThread]
        static void Main()
        {
            if (!RuntimeManager.Bind(ProductCode.Engine))
            {
                if (!RuntimeManager.Bind(ProductCode.Desktop))
                {
                    MessageBox.Show("Unable to bind to ArcGIS runtime. Application will be shut down.");
                    return;
                }
            }
            Application.Run(new Form1());
        }

    private void chkOrientation_CheckedChanged(object sender, System.EventArgs e)
    {
        if (chkOrientation.Checked == true) 
        axToolbarControl1.Orientation = esriToolbarOrientation.esriToolbarOrientationVertical;
      else
        axToolbarControl1.Orientation = esriToolbarOrientation.esriToolbarOrientationHorizontal;
    }

    private void chkHiddenItems_CheckedChanged(object sender, System.EventArgs e)
    {
      if (chkHiddenItems.Checked == true) 
        axToolbarControl1.ShowHiddenItems = true;
      else
        axToolbarControl1.ShowHiddenItems = false;
    }

    private void btnBackColor_Click(object sender, System.EventArgs e)
    {
      //Create new ColorDialog control
      ColorDialog colorDialog = new ColorDialog();
      //Show the ColorDialog and exit if user cancelled
      if (colorDialog.ShowDialog() == DialogResult.Cancel) return;

      //Get color from ColorDialog
      System.Drawing.Color color = colorDialog.Color;

            //The ToolbarControl host wrapper expects a SystemDrawingColor. The 
      //ToolbarControl type library wrapper expects an OLE_Color. The OLE_Color
      //is made up as follows:(Red) + (Green * 256) + (Blue * 256 * 256)    
      //IToolbarControl2 toolbarControl = (IToolbarControl2) axToolbarControl1.Object;
      //toolbarControl.BackColor = (color.R + (color.G * 256) + (color.B * 256 * 256));
      axToolbarControl1.BackColor = color;

      colorDialog = null;
    }

    private void btnFadeColor_Click(object sender, System.EventArgs e)
    {
      //Create new ColorDialog control
      ColorDialog colorDialog = new ColorDialog();
      //Show the ColorDialog and exit if user cancelled
      if (colorDialog.ShowDialog() == DialogResult.Cancel) return;

      //Get color from ColorDialog
      System.Drawing.Color color = colorDialog.Color;

      //The ToolbarControl host wrapper expects a SystemDrawingColor. The 
      //ToolbarControl type library wrapper expects an OLE_Color. The OLE_Color
      //is made up as follows:(Red) + (Green * 256) + (Blue * 256 * 256)    
      //IToolbarControl2 toolbarControl = (IToolbarControl2) axToolbarControl1.Object;
      //toolbarControl.FadeColor = (color.R + (color.G * 256) + (color.B * 256 * 256));
      axToolbarControl1.FadeColor = color;

      colorDialog = null;
    }

    private void chkFillDirection_CheckedChanged(object sender, System.EventArgs e)
    {
      if (chkFillDirection.Checked == true)
        axToolbarControl1.FillDirection = esriToolbarFillDirection.esriToolbarFillVertical;
      else
        axToolbarControl1.FillDirection = esriToolbarFillDirection.esriToolbarFillHorizontal;
    }

    private void Form1_Load(object sender, System.EventArgs e)
    {
      //Set buddy control
      axToolbarControl1.SetBuddyControl(axGlobeControl1);

      //Add new items to the ToolbarControl
      axToolbarControl1.AddItem("esriControls.ControlsGlobeOpenDocCommand", 0,-1, false, 0, esriCommandStyles.esriCommandStyleIconOnly);
      axToolbarControl1.AddToolbarDef("esriControls.ControlsGlobeGlobeToolbar", -1, true, 0, esriCommandStyles.esriCommandStyleIconOnly);
      axToolbarControl1.AddToolbarDef("esriControls.ControlsGlobeRotateToolbar", -1, false, 0, esriCommandStyles.esriCommandStyleIconOnly);
    }
  }
}