Bug in 1.7-A2:
This problem manifest itself in the find-in-page function as well. Any text entered is reddened - switching to another tab and back, the text is searchable.
It's a known bug http://kmeleon.sourceforge.net/wiki/kmeleon17
The line in the wiki is not descriptive:
* Typeaheadfind not working with gecko 1.9.2.
And, how would a regular user know that it affects basic functions as cutting and pasting. At least users can now search and find a record of this issue, and a work-around.