Check out the method setDragView
it represents the "handle" of the drawer.
Also, check the overdraw of your views, you could simplify your layout,
for example:
<com.sothree.slidinguppanel.SlidingUpPanelLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/sliding_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/lvReviews"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:divider="@drawable/shape_divider_comments"
android:dividerHeight="1dp"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:visibility="gone" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
android:visibility="visible">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<EditText
android:id="@+id/etPersonName"
style="@style/StyleEditText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="@string/your_name_hint"
android:inputType="textPersonName">
</EditText>
<Button
android:id="@+id/btnAddComment"
style="@style/StyleButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Add"
android:visibility="visible" />
</LinearLayout>
</ScrollView>
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
renders the same with far less overdraw