If this icon is selected then all guidelines snap
to the
nearest frame when they are created or moved. This function is
particularly useful if you want to arrange several frames aligned
exactly vertically or horizontally with each other. For this you first
magnetize
the frames and set a guideline precisely at the edge
of the frame. Thereafter the guideline is also magnetized and you can
now line up the other frames very easily and conveniently with the
first.
A second click on the icon deactivates the function again.
