Tip 1. ID the ArduPilotMega files that you are working with.
I put this at the top of the files:
// FILE: file-name
When you edit files in the Arduino IDE there is no indication of the file name you are working on. The added preamble helps a lot.
Tip 2. Add identifying information to the system file so that the CLI header will reflect the current condition of the system software.
The original CLI header shows:
The 'system' file segment that places the header file on the CLI window is:
(In the Arduino window - use Edit-->Find... "Init to get to the right place)
My modified header shows the serial port baud rates that are set, which GPS and GCS PROTOCALs have been chosen, and any special conditions that have been set:
The changes made to the system file were:
Tip 3. If you get the dreaded:
I get this message when I try to change the Sketchbook location to a different release version.
The solution is easy!
Just reboot your computer. Then start Arduino again
I know that is a pain, but that will solve the problem.
I hope these tips help.