at.js listener opens list menu when CKEditor is in readOnly mode

[JulesAchiel]

Setup:

• At.js is integrated with CKEditor
• key listener : #
• CKEditor configHelper plugin is installed to enabled a 'placeholder' text when no data is in CKEditor
• placeholder text : 'Type # to open the mention list'
• render CKEditor in readOnly mode => click anywhere in CKEditor and nothing can be done => click on the listener key '#' and the list menu is shown and accessible. => an option can be selected and is inserted in the readOnly CKEditor instance

Expected behavior: When CKEditor is rendered in readOnly mode, no interaction should be possible and the at.js list menu should not be opened or at least one should not be allowed to insert