How to add/change features of the existing application?

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开发者_开发问答 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?

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.

At any time after publishing an application on Android Market, you can upload and publish an update to the same application package. When you publish an update to an application, users who have already installed the application will automatically receive a notification that an update is available for the application. They can then choose to update the application to the latest version. So, your application must define both an android:versionCode and an android:versionName attribute in the element of its manifest.