No, the TM Lookup pane's highlights show which words from the search were found in the segment. In other words, it doesn't highlight the differences but the similarities, and the way it does it makes it impossible (visually) to use it for checking the differences.
hmm, and you're using the Alt + - shortcut to display the different matches of a segment?
Because, the differences are indeed highlighted in yellow (in the same manner as the look-up panel does when searching for words).
But apparently, WFPro just shows what has been removed from the old sentence that was in your TM, not what has been added. Far far from being ideal...
Maybe that could help:
Furthermore, TM Lookup on the source text doesn't work with the right-click menu -- one has to copy/paste the text into the TM Lookup search field using the mouse (and you can't switch between the Edit pane and the TM Lookup pane using a keyboard shortcut either).
but you can do the contrary and use Alt+F12 to insert results from the look-up panel (whether parts of it or a whole sentence) in the segment you're currently translating.