A method of entering page layout constraints into a computer. The method comprises providing a container for representing a page layout. The method further comprises providing a set of graphical objects, each having a set of object gridlines for delimiting important graphical features. Each of the set of object gridlines has a span. The method further comprises selecting and placing the set of graphical objects one by one within the container. Each of the selected graphical objects are positioned by snapping the position of the span to a non-empty gridline or by adding a new gridline. The method further comprises determining at least one pair of colliding gridlines. Colliding gridlines have a parallel direction and at least one pair of spans which at least partially overlap in the parallel direction. The method further comprises inserting page layout constraints between the at least one pair of colliding gridlines.