RadControls for ASP.NET AJAX
AllowCustomText is a property which allows users to type a random text in the RadComboBox's input area. This means that
the RadComboBox's input area can contain text that is not encountered as text of an item from the RadComboBox's item collection.
AllowCustomText is a boolean property and gets either 'true' or 'false', as a value. When it is set to 'true' - the
users are allowed to type text in the input area, when set to 'false' - the input area contains only the currently selected item's text, or text obtained
by all selected items' texts separated by comma or other character.
When AllowCustomText is set to 'true',
the MaxLength property controls the number of characters the user can type into the input area.
When EnableLoadOnDemand is enabled,
users are allowed to type in the input area, regardless of the value of AllowCustomText.