Rockwell Automation GMLC Reference Manual - Manual (Page 206)

Publication GMLC-5.2 - November 1999
Splitting the Diagram Window 169
3. While holding down the left mouse button, pull the splitter down. The
Diagram Window splits into two views.
Note: You can also split the Diagram Window by clicking in the
Diagram Window with the left mouse button and selecting
Split from the Window menu.
4. At this point you can, for example, double-click with the left mouse
button on a module in one of the views. In the example below, the
contents of the Init module was opened for viewing.