Displaying variable values - including breakdown values of their attributes - of current scope has been the most important thing to my debugging practice.
AFAIK, Netbeans PHP IDE only supports XDebug. XDebug is known to be unstable with watches and balloons (and I have had too many crashes experience) and having this defect yields Netbeans useless IMO.
I use PDT together with XDebug over the past 3 years of active PHP development and for the past few days (finally) I started using Zend Debugger. Then I realized that it has the "problem" of only displaying variables in scope (e.g. function scope), meaning, global variables and $this will not be shown, due to usability and performance concern.
The fix is pretty simple (after reading this forum response), just place watches if you want to monitor out-of-scope variables.