Originally Posted by BetterRed
Itimpi is correct in pointing out that there is a formal change request system, but some (many) enhancements are done as a result of issues raised in the forum. Presumably the developers raise the change request - Kovid even posts a link to code that implements the change to let the OP know.
Of course itimpi pointed this fact out over 2.5 years ago. I didn't want to bring to the fore an ancient thread titled "Calibre 'feature request' thread", so I separated out the posts to a new thread.
For others, if after discussing any feature you wish to learn how to submit an official enhancement request, read this page