Symptoms

There used to be HTML literal control v1 available as K2 communtity project. This control may be used for different purposes, for example to execute java script. Old version of this control (v1) does not work with K2 4.6.9 and after upgrading to 4.6.9 the HTML Literal control popup to manage the content appears to be read-only.

Diagnosis

This control was not updated to work with 4.6.9. If you dig into the html there is a div with class input-control-watermark. If you remove this via the browser dev tools then the popup can be edited.
 

Resolution 

The text box in this control requires some adjustment. In the control it is necessary to add the following before showing the textbox:

jQuery("#K2FieldLiteralInnerHTML textarea").textbox()

The new version of this control updated to work with 4.6.9 is now available on community.k2.com - HTML Literal 1.2, this is placed as a new project (separately from old version, and project containing old version shouold be remved from community site soon).