public class MyPref extends Preference {
    private static final String TAG = "MyPref";

    public MyPref(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onBindView(View view) {
        super.onBindView(view);
        View v = view.findViewById(android.R.id.widget_frame);
        if (v != null) {
            v.setVisibility(View.VISIBLE);
            GradientDrawable d = new GradientDrawable();
            d.setCornerRadius(12);
            d.setColor(0xaaff0000);
            v.setBackground(d);
        }
    }
}