如何修改C#中ContextMenu的样式？

1、我在我的程序中用到了ContextMenu,具体代码如下：
if (e.Button == MouseButtons.Right)
{
contextMenu = new System.Windows.Forms.ContextMenu();
openFileMenu = new System.Windows.Forms.MenuItem("Open a Media File <ALT+O>");
loopMenu = new System.Windows.Forms.MenuItem("Looping <ALT+1>");
playBackMenu = new System.Windows.Forms.MenuItem("PlayBack <ALT+2>");
play = new System.Windows.Forms.MenuItem("Play(&P) <ALT+3>");
Pause = new System.Windows.Forms.MenuItem("Pause(&C) <ALT+4>");
StopMenu = new System.Windows.Forms.MenuItem("Stop(&S) <ALT+5>");
Forward = new System.Windows.Forms.MenuItem("Forward a Frame <ALT+6>");
Backward = new System.Windows.Forms.MenuItem("Backward a Frame <ALT+7>");
FirstFrame = new System.Windows.Forms.MenuItem("To the First Frame <ALT+8>");
LastFrame = new System.Windows.Forms.MenuItem("To the Last Frame <ALT+9>");


openFileMenu.Click += new EventHandler(openFile_Click);
loopMenu.Click += new EventHandler(loopMenu_Click);
playBackMenu.Click += new EventHandler(playBackMenu_Click);
play.Click += new EventHandler(play_Click);
Pause.Click += new EventHandler(Pause_Click);
StopMenu.Click += new EventHandler(StopMenu_Click);
Forward.Click += new EventHandler(Forward_Click);
Backward.Click += new EventHandler(Backword_Click);
FirstFrame.Click += new EventHandler(FirstFrame_Click);
LastFrame.Click += new EventHandler(LastFrame_Click);

openFileMenu.DefaultItem = true;
loopMenu.DefaultItem = true;
playBackMenu.DefaultItem = true;
play.DefaultItem = true;
Pause.DefaultItem = true;
StopMenu.DefaultItem = true;
Forward.DefaultItem = true;
Backward.DefaultItem = true;
FirstFrame.DefaultItem = true;
LastFrame.DefaultItem = true;

openFileMenu.BarBreak = true;

contextMenu.MenuItems.Add(openFileMenu);
contextMenu.MenuItems.Add(loopMenu);
contextMenu.MenuItems.Add(playBackMenu);
contextMenu.MenuItems.Add(play);
contextMenu.MenuItems.Add(Pause);
contextMenu.MenuItems.Add(StopMenu);
contextMenu.MenuItems.Add(Forward);
contextMenu.MenuItems.Add(Backward);
contextMenu.MenuItems.Add(FirstFrame);
contextMenu.MenuItems.Add(LastFrame);
System.Drawing.Point _Point = m_ImageBox.PointToClient(System.Windows.Forms.Cursor.Position);
contextMenu.Show(m_ImageBox, _Point);

m_ImageBox.Refresh();
}

这样是实现了我想要的功能，但是我想修改一下这个contextMenu的样式，请问下应该怎么修改它的样式呢？