You should consider having the Drive Map Legend displayed all the time on the main page of Defraggler. This is important information, wanted when defrag is in process, and hard to use in the current scheme (it covers too much other stuff when invoked).
1) a condensed version would fit in the empty space to the right of the current tabs (Drive, File list, Search, Drive map).
2) on the Drive tab, the Status & Properties parts of the screen could be downsized a bit to allow another box to the left giving the Drive Map legend. (This is less desirable than option 1, since it is only visible when using the Drive tab, not all the time).
For users who don't want this on their screen all the time, there could be an option on the settings screen to turn it on or off.