Thanks for the great plug-in. Very useful.
I found that some of my logic was too long to fit in the default edit box size. Subsequently noting that other text fields in the widgets were the full width of the widget dialog, I did some poking around and found that the text edit box that widget logic adds doesn't specify a class.
Updating one line of the code:
echo "<p><label for='".$id_disp."-widget_logic'>Widget logic:</label><input type='text' class='widefat' name='".$id_disp."-widget_logic' id='".$id_disp."-widget_logic' value='".$value."' /></p>";
That does the trick for me quite nicely, so I thought I'd share the changes.
Thanks again for contributing!