For example, if you see an AIM window peeking out from behind your browser and you click on it, that window will come to the front, but the main application window will not. The Mail.app/Activity Viewer is another example. The Aqua system of layers works well in many instances, but not in all. Thank goodness that the Dock is always there to come to the rescue. I know that clicking on an application icon in the Dock will always result in not only the application coming to the front, but also any non-minimized windows associated with it. And if the application is active but no windows are open, clicking on the Dock icon should create a new window in that application.

To put my money where my mouth is, in each new article I'll build a hypothetical application that illustrates the guidelines I'm covering. Today's application is called "Paint" and will be based on the photo-illustrative icon I created in my last article. Together we will complete each step, and by the end of the project we should have a well-designed, 95%-100% Aqua-compliant application. I'll leave some room for personal preferences and the fact that Apple changes the OS every few months.

By building an application that takes advantage of Aqua's many facets, you help ensure that your application will not only look good, but have a chance of becoming a raging success. After a new user clicks on the icon of your program, the first thing he or she sees is the application interface. I know that when I review a product, I am very critical of its visual design. I usually have a short time to learn the new software, so design and ease of use are very important. Aside from those who marvel at the beauty of the command line, most users tend to react the same way.

Adhere to Window Models. Document windows, Utility windows, Click-through, Layering, Drawers, Controls. How do users open windows, how do you properly title windows?

Okay, I just told you what Apple wants you to look out for with window positions, but in the real world, not everyone uses the hiding feature of the Dock, and it is unrealistic to be able to predict where each user will place their Dock at any given day or how large they will have it. However, you can build a feature into your application that allows spacing for the Finder. You can give users the option of where to position their windows and what area of the screen not to cross. I know that BBEdit provides me with this feature, and I wish more developers gave me more control over my windows.

The simple fact is that, when all other factors are equal, where will consumers spend their money? I believe that in the long run, the best looking, easiest-to-use applications will also be the most successful. I think that's why Apple encourages developers to write programs that are 100 percent Aqua-compliant.

But limit your animations to whatever is required to communicate the necessary information. Avoid annoying animations that discourage ease of use. Ask yourself, "What do I need to show the user, and what is the cleanest way possible to achieve that?" A good example is the Mail application for Mac OS X. Whenever a new message arrives, the Dock icon changes appearance to indicate a changed state.

You Must Promise. To call your mother, to help old ladies cross the road, and to turn your cell phone off at the movies.

User Assistance. This is helping the user with the proper "next step" when performing a task. Less guesswork for the user on what to do next makes for a better experience.

Drawers. Similar to Sheets, this is a "child" window that gives users access to items that do not always need to be present. But when do you use a drawer and when do you use a palette?