I pasted the following into the CqL box:
<scope>
<scope>
<scope>
<element name="q"/>
<element name="roleinfo">
<attribute name="sprole1">lec</attribute>
</element>
</scope>
<element name="messageinfo">
<attribute name="con">1</attribute>
</element>
</scope>
<element name="course">
<attribute name="c">1</attribute>
</element>
</scope>
(the whitespace was to make the query structure clear for a student I'm working with).
The box disappeared and was replaced by gray and the word "static" (see screenshot).
Alt-tabbing away and back makes it come back as it should; so does selecting the text. If I don't do anything to get rid of the grey, it doesn't stop the query working.
I seem to remember there being a similar bug in another window though I can't recall which one...
screenshot of dialog