and 
buttons on the top toolbar. If you have two monitors, you can have the interface open on one monitor, and the model open on another. The newest Stella products have a great deal in common with earlier STELLA and iThink versions, but some things are different. We've put together some of the key ways in which interacting with models and interfaces has changed. Read through this and, hopefully, when you don't know how to do something, or something doesn't work, you can quickly figure it out. Also take a look at Tips and Tricks for getting the most from Stella, which covers many common things that may have changed.
The model and interface are now presented in two separate windows. If you have Stella Architect or iThink, you can move back and forth between the two windows using the Window menu, or by clicking on the and buttons on the top toolbar. If you have two monitors, you can have the interface open on one monitor, and the model open on another.
The products Stella Professional supports work only on the model. If a model has an interface, it will continue to do so, but it won't be visible when working with a model using Stella Professional. The isee Player works the same way.
The products Stella Designer supports work only on the interface. The model is used for computation and continues to be part of the saved file, but can't be directly edited. Published interfaces also show only the interface, and not the underlying model, though there's an option to upload the complete model, so that people using the interface online can also get access to the underlying model using isee Player or another product.
Previous versions of STELLA and iThink placed the entire interface on a large canvas, and allowed the specification of page size to determine how it would be divided into pages. Now, the interface is truly broken up into different pages, which can be added to and rearranged at will from the Pages Panel (Interface). When published, every page becomes a unique web page, making this a very natural way to organize content.
The model window is not oriented around pages. Instead, modules are recommended as the main organizing block for dealing with large and complicated models. While it's still possible to show page boundaries, these are based on the currently selected printer, and are primarily a convenience for making sure things are properly aligned when printing.
In older versions of iThink and STELLA, when using the Define Table/Graph dialog, you could choose variables from the “Available” list. Now, if you use the Table or Graph panel to add variables, there are several ways to do it.
button to add a variable, and this will bring up the Find dialog. Click once on the variable you want to add.To add a second variable or remove a variable, use the green and red plus and minus symbols under the variable list.
Every variable has a precision setting that can be changed on the Scales and Ranges Tab. You can override that for specific graphs and tables by right-clicking on the graph or table, selecting Format, and then selecting the name of the variable (or time) that you want to format.
Every variable has a range setting that can be changed on the Scales and Ranges Tab. You can also set the scale from the Graph Series Property Panel to override it, include left and right scales, and have multiple or single scales for different variables.
Arrayed variables are now specified as a one dimensional slice, followed by a set of values as in ArrayedVar[*],1,2,3. This allows you to import only the elements of an array you want, without having to import the entire thing. Graphical functions always use the complete array definition, and you don't need to import every element, just those you want to override. See Creating Import and Export Files for more details.
By default comparative graphs and tables display information for all runs that are active. If you have a comparative graph or table, and want to preserve the currently displayed set of runs, open the panel for it (by double clicking on the graph or table) and check the Stash button as described in Stash Data . You can then continue to lock run outputs in by using the 
that appears on the graph or table.
In older versions of STELLA and iThink, when you dragged an object, nothing would happen until you let it go. Now, everything is repositioned as you drag it. This allows you to see the final appearance without having to drag a second time for fine tuning, but it also means that if you're trying to put something onto a graph, or into an equation, it does the wrong thing. When you want to move an object onto a graph or table, or into something in the panel, such as an equation or sensi-parameter, hold down the Ctrl key (⌘ on Mac). The original object won't be moved, and you can drop it onto its target.
Note Dragging an object onto a graph will also usually work, and the object will be returned to the position it was dragged from.
While there are still a number of dialogs in Stella, as much as possible, the Panel is used to control model and object settings. Run Specs, for example, are a tab on the Panel that shows when you have no object selected, and sensitivity runs are set up from another tab on that same panel. The panel is also used to define graphs and tables.
Stella now gives you a great deal more control over the appearance of your model, but it no longer uses the paint metaphor for changing appearance. Instead, select a number of objects and apply styles to them, including colors and fonts. The properties shared between the objects (these will vary, depending on exactly what's selected) can then be changed from the panel.
Both the model and interface windows have an edit mode in which everything can be moved; clicking on an object selects that object, showing sizing handles if appropriate, and double clicking brings you into the panel to change the properties of the object.
The model window also has explore mode, which you enter automatically if you run the model or which you can switch to explicitly from the Mode Toolbar. In explore mode, you can't move things; instead, you have the opportunity to change the values of any constants in the model and see the results via Stella Live. Double clicking will still bring you to the properties for that object (and switch you to edit mode).
The interface experiment mode keeps you in the same window but lets you test interface behavior. You can't move things in experiment mode, but double clicking will open the panel and switch you to edit mode. The interface also has presentation mode (full screen or windowed), which hides the rest of Stella, so you only see the interface. Presentation mode mimics a published interface and double clicking does not have any effect. Use the Esc key to exit presentation mode.
To delete something, click on it to select it, then hit the Delete key, or right-click and select delete.