I can't see how searching a project group actually searches the packages the project depends on. Testing it, it doesn't seem to.
The Project Group feature does not search packages. It is only a set of projects which can be built in one go.
I have not heard of a specific package group. Such a group can be made with a meta-package + its dependent packages of course.
A single project has a list of dependent packages. They (and their paths) are found after the IDE has seen them
once. No search path settings are needed. Pretty neat, ha?
Currently you cannot include / exclude whole units by IFDEFs. However you can use IFDEFs freely inside a unit. For example if you put all Windows specific code inside
{$IFDEF MSWINDOWS}
then the unit looks practically empty for other targets.
If the Windows specific code is called from inside {$IFDEF MSWINDOWS} in other units, everything works fine.
You can use IFDEFs also in uses section, so the Windows specific unit is used only when needed.
Earlier posts ... :
Shift-F11 by default adds the current editor file to the current project. It is not relevant to your problem.