add/remove items from right-click context menus

[#1]

Does anyone know how to add/remove options/items from the right-click context menu in the thin client similar to the 'Properties', 'Clear, 'Export to Excel', etc.? See example of existing AJAX right click context menu below. Can this be further customized?

[Anonymous]

It cannot be customized, as far as I know, but can be restricted.
First, some options can be disabled by the security permissions. For example, if there is no access to sheet object properties, the "Properties" option is disabled. See security tabs in the document properties and sheet properties.
Next, there is an option in the general document properties that hides unavialable menu options. That is, the disbaled options just do not show up.