private void onRelease(boolean stayForLoading) {

        tryToPerformRefresh();

        if (mStatus == PTR_STATUS_LOADING) {
            // keep header for fresh
            if (mKeepHeaderWhenRefresh) {
                // scroll header back
                if (mPtrIndicator.isOverOffsetToKeepHeaderWhileLoading() && !stayForLoading) {
                    mScrollChecker.tryToScrollTo(mPtrIndicator.getOffsetToKeepHeaderWhileLoading(), mDurationToClose);
                } else {
                    // do nothing
                }
            } else {
                tryScrollBackToTopWhileLoading();
            }
        } else {
            if (mStatus == PTR_STATUS_COMPLETE) {
                notifyUIRefreshComplete(false);
            } else {
                tryScrollBackToTopAbortRefresh();
            }
        }
    }
if deltaY > 0, move the content down

@param deltaY
ptr-lib/src/in/srain/cube/views/ptr/PtrFrameLayout.java