Without any modification, using VS2013, the SampleSite.sln HtmlEditorExtender demos provided throw the following error when trying to use fore or back color tool:
0x800a139e - JavaScript runtime error: Sys.InvalidOperationException: 'unselectable' is not a property or an existing field.
0x800a139e - JavaScript runtime error: Sys.InvalidOperationException: 'unselectable' is not a property or an existing field.