Thanks for the reply..So nice of you

to point my concerns.
I fully agree with u on the fact that the enhancements (so I think !) I seek may or may not

be common interest to all.
However I only intend to retain all the features that exists now, if at all, I tweak with the code myself

. Well, on the patch suggestion, I agree its a pain for original creators if I/somebody modifies their code and give them back to proceed further. (In fact, I would not like it myself unless the changes are simple enough).
You are right that my plugins (if at all I create) may not be compatible with revisions of default ones of calibre versions that may follow...However, a glimmer of hope

is that Calibre allows to add plug-ins and also to simply disable/enable by choice.
Thanks to your suggestion, I have contacted Mr.Kovid on these by a private mail, and hoping for a reply

. Also, I started a new thread

on these, and hoping to gather other's thoughts.
Thanks a lot, once again.