How to add/change features of the existing application?

Question

Is it possible to add or change the existing applications?

For example, I would like to add a new floating window following the current people when I open the contact manager.

I just want to change it a little bit. And I don't want to rewrite all the features of contact manager.

Is it possible to do this?

As I understanding, the view of the contact manager is controlled by the activities of the "contact manager" application. How can my application react when the user opening the contact manager?

Answer 1

Is it possible to add or change the existing applications?

Only by rebuilding the firmware. You are welcome to contribute your changes to the Android open source project for potential inclusion in future versions of Android, though.