It would really be useful to be able to set blocks of data in the editor in different colors. For example, you are working on a flat file of 50 records. The record length is fixed at 1041 bytes. Using various pale background colors, you could set it to mark the first 1041 bytes one color, then the next 1041 bytes another color, so you could quickly see the beginning and ending of records. This would make it easier to quickly edit blocks of data.
The user could also define offsets, such as a header or trailer record that might not be as long as the main body records.
The block coloring could also be instructed to look for a certain character (in hex or ASCII) or set of characters to mark the end of a record (i.e. Unix, x'0A', MS-DOS/Windows x'0D'x'0A', EBCDIC x'0D'x'25') This would allow marking of variable length records.
Not to infringe on potential copyright issues, but an excellent example of what I am describing is used in WinHex. I notice that also many progam IDE packages' data editors that I've used also have this feature of marking "rows" or blocks of data.
I've found Notepad++ to be an excellent tool and look forward to this enhancement.