Feedback from Birthe.

**Buggy behaviour**

Missing this easy hint for "new" or inexperienced user
<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/236111/content">

**Expected behaviour**

* The placeholder text says Begin of the insertion&quot;Add aEnd of the insertion Begin of the deletion &quot;Type toEnd of the deletion comment. Begin of the insertionType @ to notify people.&quot;End of the insertion Begin of the deletion You can @mention users.&quot;End of the deletion