Amend c8c7fc18af5f to handle window resize-tiggered updated

Issue #1787
[dtd mode] Add
Fix drag/drop on Chrome by setting an image src

Work around a Chrome regression where it aborts the drag if the
setDragImage image is src-less.

Closes #1810
[tern addon] Compensate for fact that call start pos is a column, not char offset

Closes #1811
Allow styling of lines from mode tokenizers (experimental)