http://www.intellij.net/tracker/idea/viewSCR?publicId=18875
Provide toggle button to wordwrap the contents of the two compared files. (Default wordwrap off)
Tricky to see at a glance where differences are if they are at the end of long lines - have to scroll the display left -> right.
If the files could be displayed wrapped at the width of the view, then you could tell at a glance.