Venapps, in contrast with Vensim, are organized around a single main active window or screen. This is intended to simplify interaction, minimize clutter, and direct activity.
When a Venapp starts it gets a new window that is, by default, maximized. The Vensim Workbench is hidden so that all interaction is with the one main window. The screens are designed to be resizable so that relative positions are maintained if the window is no longer maximized.
The contents of the Venapp window are built up from the different controls available. You can draw text and lines, show variable values and display the output of Vensim tools. Each screen is given a name, and referenced by that name in the .vcd file. Names can be up to 14 characters long, and can contain any letters of numbers, but not imbedded spaces. To define a screen, begin the line with :SCREEN and then the name you choose, as in:
:SCREEN HELLO
Nothing else may appear on this line.
A Venapp always starts from the first screen in the definition file, although other than that, there is no restriction on the order screens are defined.
