What feature is missing or hidden in Notepad++, that can be added while keeping it still the small, fast and efficient source code editor that it is?
Have you found a feature to be missing only to later discover a way to achieve this anyway, perhaps with a plug-in?
One of the few things I miss in Notepad++ is Crimson's column edit mode, that let's me select a range of lines and edit them at the same time.
I can't stand the fact that everytime I save or open a document, I start from the program directory instead of the directory I used last time.
If you have a file like this
Line 1
Line 2
and lines 3-10 are blank, pressing enter on line 10 will indent by two spaces, just because line 2 is indented. This often annoys me. I think it should only auto-indent, if the line you're on is already indented.
My most wanted plugin for Notepad++ would definitely be a multi-line "Find/Replace in files..." functionality. I love Notepad++ and think it's an awesome program. Sadly, this kind of functionality is needed. Especially if you need to replace blocks of text in multiple files. Granted you can do a search for the first line and the paste over... but that is tedious. Also, a regular expression could be used to grab multiple lines, but this doesn't always work out.
Notepad++ doesn't allow the selecting of a User Defined Language, by default, which is frustrating if you constantly work with a custom language which is not on the language list. :-(