how to fix seekbar-bar-thumb-centering-issues

Set minHeight and maxHeight same as the height of seekbar. eg

<SeekBar 
    android:id="@+id/PP_Player_SeekBar"  
    android:thumb="@drawable/music_player_playerhead"
    android:paddingLeft="8dip"   
    android:paddingRight="8dip"                 
    android:progressDrawable="@drawable/seekbar_drawable_xml_background"
    android:layout_width="236dip" 
    android:layout_centerHorizontal="true"
    android:layout_height="wrap_content" 
    android:layout_marginTop="47dip"
    android:minHeight="11dip"
    android:maxHeight="11dip" />

See the following url
http://qtcstation.com/2011/05/android-how-to-fix-seekbar-bar-thumb-centering-issues/