Z Probe Offset plugin

Question? I don't know where to ask this, so I'm posting here. How does this plug in work. I have it installed, how would i increase the offset, just hit the "+" and thats it? What is the "pencil" for? Any help would be appreciated, Thanks

The pencil stores the value to EEPROM. I don't think it actually uses the value unless you do it. And even if the value is used, it won't be remembered after you power off the printer, if you don't click the pencil.