You can cancel the 'OnClientDropDownOpening
' by using the code "args.set_cancel(true)
" if there are no items in the RadComboBoxItems collection. You can check the number of items from client-side. The following documentation will help you in achieving this:
Also checkout the following forum which discussed about setting the dropdownwidth according to items.
KB Article - Set the Height of RadComboBox based on number of items