it creates 4 letter key IDs (same as in pot/po files)

kid is language code of Koshin. It is better to use a code
from the ISO 639 private range.

We need to handle fragment span in case the HTML span is not provided
by the source application.  According to the MS spec it is allowed.

The old code assumed that the source app would always provide an
HTML span.  Apparently some apps don't, and only provides a fragment
span.

This avoids permanent calls to the SwHeaderFooterWin::Paint method. The
loop is now broken and the cursor doesn't blink anymore.

After having triggered the separators using a mouse-over, hide the
separator when clicking in the main body or typing.

This reverts commit 2dea0dab.