I've been using Defraggler for some time now, and I love it. My only suggestion would be to add a legend of the different colors used in the drive mapping so you can know what each block means. There's plenty of empty space in the application under the Status and Properties headings (When the application is in full screen mode) where you could put something like this.
First option under Help menu. (I use a French translation, don't know what it is in English). And if you're asking yourself what are these lightly oder darkly colored blocks, it's simply if they are "full" of files or not
ive wondered about those diff colored blocks myself! red, green, blue all the wonders of the rainbow. yesterday when i did a defrag on hard drive D disk, there were still a lot of red blocks left after the session had ended.
Click on these blocks. You'll see "inside" them. Probably the MFT. Or some other Windows thing...(like, yesterday I tried PerfetDisk in trial version, and the only good thing that stupidity did was to show and defrag a file that was in ten thousand fragments ?_O)
wow i clicked on one red block and it revealed 4,000 files! some other blocks revealed 500 to 1,000 files..etc all that on local disk C
Remember, a red block means there is at least one fragmented file in it. If you have 1000 files, maybe there is only one or two fragmented files