1.0dev: fix small glitch related to #9619, also "lock" the editor scrollbar.
1.0dev: fix small glitch related to #9619, also "lock" the editor scrollbar.

Otherwise the scrollbar could jump to the top after a resize following
an XHR, and the cursor can get out of view.


pkdevbox/trac,pkdevbox/trac,pkdevbox/trac,pkdevbox/trac