For some time now I've been looking for an accessible PHP debugger. NetBeans is based on Java Swing, which means it is poorly accessible at best. Eclipse is quite accessible, but really heavy for what I'm looking for, and the debug configuration screen is pretty poorly accessible.
MacGDBp seems to be a partial solution, and it's open source.
Using MacGDBp, and MAMP, I am able to step through code*, view the call stack, view the values set in the variables in the current scope, and pause execution at a given breakpoint**.
* Although I can step through code, the code view isn't very accessible, so it takes a bit of work to understand exactly what line is about to be executed.
** I have yet to find a way to set a breakpoint in MacGDBp, it requires clicking a line of code with the mouse, but I can set a breakpoint in code by calling xdebug_break().
Since 98% of my use-case for a PHP debugger is to have code execution pause, to see the call stack, and to check the value of a variable, then MacGDBp will definitely get the job done. I'm fortunate to work with an awesome team that can help with the rest.
While researching MacGDBp I came across these useful articles: Debugging your PHP Code: XDebug on MAMP with TextMate and MacGDBp Support | TechnoSophos and Debugging Drupal with MacGDBp | Trellon.