Via Lars Fosdal:

In Tools|Options, Environment Options, Environment Variables – under User Overrides, add a new override

Variable name: DCC_Define

Variable value: billmeyer

This causes a define for billmeyer to exist for anything that you compile in your IDE, across all units, all projects.

Which means you can sprinkle your code with

{$ifdef billmeyer}{$hints on}{$endif}

or

{$ifndef billmeyer}{$hints off}{$endif}

or even isolate out the parts of the code that currently is in development so that it doesn’t get built in the build system.

I believe it was +Uwe Raabe who revealed this gem to me.