android 5.0及以上，seekbar thumb 透明效果出现父布局背景颜色的解决方法

在seekbar中添加  android:splitTrack="false" 即可

1. <SeekBar  
2.            android:id="@+id/seekbar"  
3.            android:layout_width="match_parent"  
4.            android:layout_height="wrap_content"  
5.            android:max="@integer/max_step"  
6.            android:maxHeight="@dimen/seekbar_height"  
7.            android:minHeight="@dimen/seekbar_height"  
8.            android:padding="0dp"  
9.           <span style="color:#ff0000;"> android:splitTrack="false"</span>  
10.            android:progress="0"  
11.            android:progressDrawable="@drawable/bg_seekbar"  
12.            android:thumb="@drawable/bg_seekbar_thumbs"  
13.            android:thumbOffset="0dp" /> 
    

from:http://blog.youkuaiyun.com/jacklog/article/details/50067227