To the file system, a PHP project is just a bunch of text. To the programmer, it's a complex stack of abstractions and logistical constructions.
While some IDEs treat the code like text files, phpDesigner takes the programmer's view. It offers an elaborate set of templates and editorial menus that help you work with the logistical structure.
This structure is used in a variety of ways. The code completion learns your libraries, the search tool highlights any word you select with a double click, and the code explorer displays your code in a big tree. Poking around your code this way is quite useful, especially if it's not code that you wrote. The logical structure is often a bit easier to understand than raw text. There are separate lists for the constants, functions and variables. If you want to find one, you click on that tree and the declaration appears.
The IDE also offers a fairly large collection of templates that can be useful if you can't remember the exact way to construct some method or line. You hit the Class button and
class appears in your code with the curly brackets. If you work the buttons correctly, you can write quite a bit of parsable code simply by clicking.
PhpDesigner is one of the few IDEs that carry its own version of PHP with it. If you create a PHP file, you can execute it and get the results in a number of different forms that range from the raw input to the display in your browser. I had mixed results with this feature. My version of Drupal, for instance, wouldn't execute correctly at first because the debugger wasn't connected properly.