@Override
    public void onDestroyFloatView(View floatView) {
        ((ImageView) floatView).setImageDrawable(null);

        mFloatBitmap.recycle();
        mFloatBitmap = null;
    }
Removes the Bitmap from the ImageView created in
onCreateFloatView() and tells the system to recycle it.
third_party/DragSortListView/src/com/mobeta/android/dslv/SimpleFloatViewManager.java