the scroll wheel (or button) usually is related to the part of the screen, above which the cursor is located (even without this position having the focus), the up/down page-up/page-down buttons are usually related to the part of the window which has the focus.
a part of the window can be the window itself, a frame, a scrollable layer (as in our case here), a dropdown, a textarea, some other elements ....
btw: the scroll wheel can also sroll left right if the cursor is above the right position and horizontal scrolling is available ... check it out ...
christian
and remember: only a CRAY can run an endless loop in just three seconds.