Hi Jeroen, I really like jkdefrag however I find the colour scheme to be a little lacking in contrast. If I may be so bold as to suggest the following alterations to the colour scheme of the GUI I think it would improve the visual look and help with the identification of different features in the display. The majority of the changes are to increase the contrast between the different types of file marking. I include a screen shot of the current colour scheme for comparison.
The colours suggested are as follows: Empty (#000000)
In use (#2D4880)
System files (#5CCC63)
In addition the mock up image includes a narrow darker grey border surrounding the main display to help define the data region from the window and text regions:
Thanks again for developing this the great program, I hope my suggestions are useful.