1. A computer-executed method of displaying changes to a data file comprising: associating an annotation with a programming module of a baseline file on a computer; displaying on a display of the computer in an unsegmented window of a graphical user interface the baseline file as a tree structure having a plurality of nodes, each node representing a programming module of the baseline file; and displaying the annotation, on the display of the computer in the unsegmented window of the graphical user interface, proximate to the node that represents the programming module with which the annotation is associated, the annotation including a plurality of selectable messages displayed proximate to each other in order to facilitate visual comparison, each selectable message describing a modification made to the baseline file by a different contributor, the annotation indicating that the modifications produce a conflict, the conflict being resolvable within the unsegmented window by a selection of one of the selectable messages.