java.lang.NullPointerException at
com.example.draggridview.DragGridView$1.run(DragGridView.java:145)
mStartDragItemView.setVisibility(View.INVISIBLE);

#	modified:   DragGridView/res/layout/grid_item.xml
#	new file:   DragGridView/res/values/colors.xml
#	modified:   DragGridView/src/com/example/draggridview/DragGridView.java