In your poll questions, you acknowledge that there are many existing editors. So, I would think the natural question that comes to mind is what you intend to offer that existing editors do not?
Certainly one such offering would be anything that could be linked somehow to AHK. For instance, the user's ability to include and use their own script files. That would seem to be a natural, don't you think? Besides, although some editors may offer a small scripting language (for example, NoteTab Light does offer such a thing), it always seemed to me to be a waste of time to learn someone else's scripting language if it was not Open Source so that you could not make improvements to the language yourself. Of course, with AHK, there is a large existing user base. So, there are many existing benefits associated with letting people use the AHK scripting language with your editor. In fact, it seems to me that would be the primary attraction for your editor. Wouldn't you agree? If not, perhaps I am not understanding your intent in providing this editor.
Another possibility would be some nice advanced editor functions that are not usually included wth existing editors. The things that come to my mind are column-based operations - such as the ability to move entire columns of text to the left, right, up or down. Also, the ability to move existing text in the same way - that is to indent or remove existing columns. I find those features to be very useful and I tend to use those sorts of things very often. If you were to include those kinds of features, IMO, it would be most useful. Based on my experience, it should also be fairly easy to code. In the same vein, it is also fairly easy to change the case ot text. I find that modern freeware editors have only recently begun to offer those features. You can either highlight a string of text and change its case - or you can copy a string to the clipboard and make the changes there. The most usual kinds of case changes are to change it to upper, lower, capitalized, inverse or sentence case. NoteTab includes the ability to split and join lines which can also be very useful.
If you like, please send me a PM and I will be glad to send you links to some of the threads in this forum that discuss these issues and even contain existing AHK code to accomplish these things. You are most certainly welcome to use all or part of my code if you find it helpful.
Before doing much coding though, I would suggest you review the features of the most popular existing editors. Have you seen the site called the "46 Best-Ever Freeware Packages?" It includes a section for editors and following are the seven freeware editors they recommend as "The Best".
I do not agree with their inclusion of EditPadPro. FYI, I find that many of its best features are only included in the "payware" version and I have found problems with the freeware version. It's always a good sign if the author offers a "pure" freeware package and does not "hold back" any of the good features to include them with the payware version. Of course, they do that in order to entice people to buy the better quality version which means that the freeware version is lacking some of the better features. That shouldn't matter too much to you because, I think your primary interest lies in reviewing the features of these editors.
Anyway, here they are:
[1]
http://www.editpadpro.com/editpadlite.html - Free for non-commercial use, Windows NT and later
[2]
http://www.flos-freeware.ch/notepad2.html - Freeware
[3]
http://www.notetab.com/ntl.php - Free for the LITE version, but they offer a payware version with some higher quality features
[4]
http://notepad-plus.sourceforge.net/uk/site.htm - Open Source Freeware - no payware version
[5]
http://www.pspad.com - Freeware
[6]
http://www.context.cx - Freeware
[7]
http://www.crimsoneditor.com - Freeware
I may be mistaken, but although EditPadPro says it is free for non-commercial use, my recollection is that only their "LITE" version is free for non-commercial use. I seem to recall that you have to send them money if you want to access their full version and judging from the freeware version, I didn't think the full version would be worth the money. I hope I am not mistaken about that.
I would recommend you look most closely at the "Open Source" freeware editors. Anyone who is willing to make their source available means that there's a good chance their source has been improved by other programmers who have worked on it. Of course, you'll need to check into that for yourself.
Some other editing features that would seem to me to be valuable to people using editors would be some control over the formatting of paragraphs. For example, being able to specify hanging or indented lines at the beginning of a paragraph. Ususally those kinds of things are only found with big, full-featured word processors, but it seems to me that it would be a nice attraction for a text editor, too.
Another feature that I find very useful is "number insertion". That is the ability to specify a sequence of numbers using a starting number and increment and then inserting those numbers into a specific column and row number either with leading zeros or leading or trailing other characters. For example, specify that you want to insert the numbers 1,005, 1,008, 1,111, 1,114, ... into columns 7 through 12 of rows 101 through 200 and you want to have the numbers appear with leading zeros where applicable and also with a comma separated number for those numbers greater than 1,000. This kind of thing comes up quite often in certain kinds of applications - such as statistical applications.
I once wrote some code to handle those routines (number insertion). They were written in Delphi, but they shouldn't be much of a problem for you to understand and translate to AHK. Once again, if you are interested in those routines, just send me a PM, and I will be happy to send you a link to a thread in this forum that explains how you can access the code.