Where can I find out about available IDE preference options?

It is possible to alter the behaviour of the IDE by changing the preferences.txt file. But without a list of the available options and some description of what they do one is stumbling around in the dark.

I have searched the Arduino website and have not found more than the briefest mention of IDE preference options. We should not be forced to rely on very inefficient and risky trial and error and luck because of a lack of access to appropriate information.

Clearly a lot of fine people have gone to considerable effort to craft code for IDE options. But what was the point if they are hardly used because few people know what non-default options are available or what they do?

It's likely that the text file is intended to be altered only by changing settings in the IDE GUI. I could be wrong, but isn't the IDE open source?

aarg:
It’s likely that the text file is intended to be altered only by changing settings in the IDE GUI.

This is incorrect. There is only one rather brief preferences ‘page’ in the IDE, and at the bottom it states "More preferences can be edited directly in the file ".

aarg:
I could be wrong, but isn’t the IDE open source?

The Arduino is intended to be very easy for programming novices to use. I don’t think it’s reasonable to expect them to wade through large amounts of intricate java code to try and work out from it, perhaps partly by ‘reverse engineering’, what preference options are available and what they do.
If the options are clearly documented in one or more places in this code then I suggest that the content of this documentation should be made available directly from the Arduino IDE and/or the Arduino website.

What specific problem or deficiency would you like to change by editing the settings?