Toad 10 has problems in the editor when highlighting. See below for steps to reproduce:
1. Go into editor in TOAD 10.0
2. Type any phrase with some underscores: eg p_form_id
3. Hover your mouse over the word form .
4. Double click
In TOAD 9.7 the word form will be highlighted. In TOAD 10.0 the entire word p_form_id highlighted.
When developing code for speed it was far more useful to have the single words surrounded by underscores to highlight.
Waiting for fix in a future release Toad for Oracle