When redDEBUG is active, it will present a fixed footer bar with several diagnostic tools, including the following:
Joomla! diagnostics and execution
It contains general execution and diagnostic information like execution time, allocated memory, number of files read and general PHP execution and environment information.
Even if development mode is off, this stacked window will present with any notice, deprecated message and warning that pops up during the execution. So now your execution window can be clean and you can focus on this red warning to notice there are some warnings you need to take care of to clean up your code.
This stacked window presents with all the plugins-related information, including the executed triggers and their time and memory consumption. Specially useful to detect bottlenecks coming from plugin execution.
Related to the plugin information, the event window displays the system, content and every other events that are being triggered, with their plugin-related information to cross-match between these two windows.
Another stacked window, made for displaying information related to modules, including each module's diagnostic information, content, parameters and other information like their position.
Since Joomla! can contain a lot of parameter-based display, this stacked window presents with the active template parameters being used in the particular diagnosed view.
It contains the Joomla! global configuration used.
The user window is particularly useful for diagnosing the logged-in user information, including all their settings and stored data that affect this particular user.
This contains the information related to the Joomla! installation, including its version, development status and released date, amongst other general information.
PHP-related information and diagnostics
The request window presents with all the parameters that are being transported to the latest call, to diagnose client/server communication.
This window contains information about every single processed PHP file, and their type information.
For a deeper view in PHP, the classes window presents with all the used classes within this execution, including the component or the file where they are executed.
This window contains all the constants used within this execution, and their respective values.
For regular PHP diagnostics, this window presents with all the server environment values, which are handled by PHP itself.
Also for allowing session debugging, this window presents with every session variable set for this execution.
Just as its name says, this window presents with all the cookies being used in the current execution.
PHP Initialization file (php.ini)
This window presents with every single variable (local and global) set in the php.ini file for this execution.
When you are experiencing an execution error (that leads to a 404 or 500 error for instance), redDEBUG will present with a diagnostic window to help you narrow down and track the origin of the error. The diagnostic window contains the specific error line (and code) of the error and each line of the execution stack, to help you get to the actual problem with the code or Joomla!.