What I want is that the 1st time that the user open my app the left panel can use the full screen!
then I need to resize it.
After reading the SlidingPaneLayout source :SlidingPaneLayout.java, you will find DEFAULT_OVERHANG_SIZE = 32 in this class as the default size of the overhang for a pane in the open state.
Since this is a private static constant，you need to change it into a variable and create its set method.
Take care of onMeasure() method and good luck.