Hi @sjchao 
Your commit is cool, but did you consider another situation?
That's one scrollView A contains some sub-scrollview B, C, D...
When in the CCScrollView:beforeDraw of C, the method of `m_tParentScissorRect = CCEGLView::sharedOpenGLView()->getScissorRect();` may return the scissor rectangle of B rather than A, Right?