Notification Area panel applet

I have a lot of problems getting this applet to work correctly. In attempting various things I clicked on the Clear Known Applications button, but now I want it to display all applications. There is no "undo" after clicking this button. I removed and replaced the applet, but it still shows only a few applications. In other words, it knew I wanted to "clear all known applications" from a setting in a config file somewhere. I want to nuke this config file to put it back to the original settings, but I can't find any config file for it. What is the name and location of the config file for the Notification Area applet? Or if it inside another config file, which one and where is it?