The Enabled extender property wasn't always honored causing the AutoComplete feature to work even if it has been disabled in the designer.
TextBox control with the PasswordChar property set to a non-null character could be autocomplete-enabled, thus revealing passwords in the autocomplete drop-down lists.
Autocompletion in the ListView and TreeView label editing text box didn't work with the built-in FileSystem, History and MRU string sources.
When a TreeView/ListView label editing was active and the Form was closed, an unhandled System.ObjectDisposedException exception was thrown causing the application to terminate.
Documentation for the component is context-sensitive and it is integrated with the Visual Studio .NET Help Collection, including Contents, Index, Search and Dynamic Help.
When all the autocomplete options had been cleared in the drop-down Options extender property editor, an invalid initialization statement was generated into the InitializeComponent method.