Bug on lamp icon in text editor

when following the tutorial 'Creating a Qt Quick Application' there is a reference to click the lamp icon.
that icon appears to be clickable only if the horizontal scrollbar is one the left edge. If the scrollbar is moved toward the right edge by delta pixels, the icon becomes no more clickable but there is a clickable area exactly delta pixel on the left of the icon. It seams that the clickable area does not follow the icon but remain on the position where it were created