如何在文本框中使用父级的上下文菜单

I have a listbox with several controls. Each control contains an custom autocompletebox which contains a System.Windows.Controls.AutoCompleteBox. When I right click on the control a custom contextm menu shows up. But with a right click on the textbox there appears the default contextmenu of the TextBox (with Copy, Cut and Paste). I have a listbox with several controls. Each co