The KDebugDialog Handbook
This document describes KDebugDialog.

What is KDebugDialog?
It is a dialog box for managing diagnostic messages at runtime.
If you simply start "kdebugdialog", you will see a list of "areas", that can be disabled or enabled. A kdDebug(area) call in the code will show something in the debug output only if the area is enabled.
Note that kdWarning, kdError and kdFatal always appear, they are NOT controlled by this setting.
If you start "kdebugdialog --fullmode", then for every severity level you can define separately what should be done with the diagnostic messages of that level, and the same for each debug area.
In the full mode, the following settings are available:
Output: In this Combobox, you can choose where the messages should be output. The choices are: "File", "Message Box", "Shell" (meaning stderr) and "syslog". Please do not direct fatal messages to syslog unless you are the system administrator yourself. The default is "Message Box".
File: This is only meaningful when you have chosen "File" as the output and provides the name of that file (which is interpreted as relative to the current directory). The default is kdebug.dbg.
Area: The areas which should only be output. Every message that is not mentioned here will simply not be output (unless this field remains empty, which is the default, and means that all messages should be output). You can enter several areas separated by commas here, and you can also use area ranges with the syntax start-end. Thus a valid entry could be: 117,214-289,356-359,221. NOTE: Do not use whitespaces.
Apart from this, you can also tick the checkbox "Abort on fatal errors". In this case, if a diagnostic message with the severity level "KDEBUG_FATAL" is output, the application aborts with a SIGABRT after outputting the message.
When you close the dialog by pressing OK, your entries apply immediately and are saved in kdebugrc. When you press Cancel, your entries are discarded and the old ones are restored.
Credits to Kalle Dalheimer for the original version of kdebugdialog