Only verified in QtWebKit2.3 so far, but may also be present in QtWebKit1 in trunk and Qt5.
Open any page with a fixed width in the QtTestBrowser, and resize the window so you get the horizontal scrollbar.
The left most button pointing left, will move the slider and the page to the right.
The right most button pointing right, will move the slider and the page to the left.
And the extra left button next to the right button, will move an entire page to the left.
So left and right one line has been mixed up somehow, and the extra left button at least moves left, but now triggers page moves instead of line moves.
This might be a duplicate of bug #105014.
*** This bug has been marked as a duplicate of bug 105014 ***