I thought this was code - between 4.0.1 and 4.0.2, the paginggridscroller on a Grid stopped working.
Spent considerable time in the debugger to find that in 4.0.2, with my own theme, that the scroller child DIV (-ct) is positioned nowhere near the actual scroll bar. As a result, when you move the scroller, nothing happens.
This behavior does not take place in 4.0.1, or in 4.0.2 if I use ext-all.css.
Comparing it to my generated theme, I notice the following is in ext-all, but not in my theme: