When viewing Messages with the Navigation block (and any other blocks) docked, clicking on a message contact opens the conversation to the right of the list of message contacts. When the list contains senders which are not contacts the following message displays under the list of senders, "(These messages are from people who are not in your contacts list. To add them to your contacts, click the "Add contact" icon next to their name.)" The text of this message is all displayed on one line which then leaves very little screen space to display the conversation. The resulting display of the conversation is very jumbled. http://screencast.com/t/WbK5GB7EA
This behavior has been introduced somewhere between 2.9.3 and 3.04. In 2.9.3 the text below the list of senders wraps across several line leaving ample screen space to cleanly display the message conversation. http://screencast.com/t/3YfiGbnrmA
STEPS TO REPLICATE
NOTE: The steps below leverage forum posts to generate messages needed to see the issue. However, any activity that generates messages from users with which the recipient has not previously conversed will allow for replication of the issue.
1. Go to Site Administration > Plugins > Activity modules > Forum.
2. Ensure that "Use email address in reply" is selected.
3. Create four new users.
4. Create a new course.
5. Enroll one of the users from step 1 as an instructor and enroll the other three users as students.
6. Login in as the instructor and create a new forum with forced subscription enabled.
7. Login as each student and make a post in the forum.
8. Wait approximately 30 minutes for the forum posts to be emailed.
9. Login in as the instructor and go to Messages.
10. Dock the Navigation block and any other available blocks.
11. Observe the instructor has 3 unread messages, one from each of the students. Under the list of students is the message "(These messages are from people who are not in your contact list. To add them to your contacts, click the "Add contact" icon next to their name.)"
12. Click on the name of one of the students.
The "(These messages are from people who are not in your contact list. To add them to your contacts, click the "Add contact" icon next to their name.)" message does not text wrap so the message navigation consumes nearly the entire horizontal screen space. Only a very narrow column remains to display the conversation with the student.
The "(These messages are from people who are not in your contact list. To add them to your contacts, click the "Add contact" icon next to their name.)" message text wraps allowing the screen space to prioritize display of the conversation with the student.
I replicated this issue in a 3.0.4 environment. The institution reporting the behavior recently upgrade from 2.9.3. I test on 2.9.3 and could not replicate the issue there.
ADDITIONAL INVESTIGATION NOTES
I have replicated the issue using both the Clean and More themes.
The limited screen space for displaying the message conversation makes it very difficult to read the conversation. Depending upon screen resolution it may be nearly impossible to use the text field to respond to the message. At best the user has a very small text field. The issue is particularly challenging for instructors at the start of a term when they are likely receiving messages from many new students.