Palette Search suggestions
The user should be able to exit the palette searching function by invoking the Palette Search once again (like toggling for note-entry), as if pressing the escape key.
Pressing Escape exits palette search and again brings the focus back into the score, but in appearance it doesn't look like it since the palette search key still remains, and the original palette workspace section remains as still in search mode. I would suggest that the behavior become as if an empty search were in place, bringing back into view how the workspace was with all potentially open palettes previous to entering into "Palette Search".
And even if it was decided not to remove the search-key upon pressing esc (or palette search toggling as suggested), still, the previous open/closed status of the palettes should be retained rather than lost after the search-key has been erased.
Hope this helps with accessibility/functionality in future.