Use a fragment from a separate package (app) while maintaining resources intact. (Not tested extensively, specially with themes). Note: The remote fragment should be self sufficient and wouldn't be able to interact with dependancies of the main application or vise-versa. [See http://stackoverflow.com/questions/10792136/classcastexception-while-d…

RemoteFragment.java

package com.example.api.extension;

import android.app.Fragment;
import android.content.Context;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class RemoteFragment extends Fragment {

    public static final String ARG_PACKAGE_NAME = "ARG_PACKAGE_NAME";
    private Context mRemoteContext;

    public Context getRemoteContext() {
        return mRemoteContext;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Bundle args = getArguments();
        String packageName = args.getString(ARG_PACKAGE_NAME);
        if (TextUtils.isEmpty(packageName)) {
            throw new RuntimeException("Package name cannot be null!");
        }

        try {
            // Get the remote package context
            mRemoteContext = getActivity().createPackageContext(packageName, Context.CONTEXT_IGNORE_SECURITY);
        } catch (NameNotFoundException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public final View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // Create the LayoutInflater from remote context so resources
        // are retrieved appropriately
        return onCreateRemoteView(LayoutInflater.from(mRemoteContext), container, savedInstanceState);
    }

    /**
     * Override to create view from remote context.
     * See {@link Fragment#onCreateView(LayoutInflater, ViewGroup, Bundle)}
     * 
     * @param inflater
     * @param container
     * @param savedInstanceState
     * @return
     */
    public View onCreateRemoteView(LayoutInflater inflater,
            ViewGroup container, Bundle savedInstanceState) {
        return null;
    }
}