Short explanation first:
We have quite complicated .prf files system in our project:

• one main.prf containing basic variables definition (especially root path for source code tree, e.g. SRC=/some/path). Every other prf, pro uses load(main) in the first line.
• for each library in our project we have separate libraryname.prf file to simply use library in this way: CONFIG += libraryname
  Each libraryname.prf file loads main.prf, adds path to INCLUDEPATH (relative to SRC variable from main.prf) and adds library to LIBS and also adds other libraries to CONFIG when required.
  All prfs are in one directory added to qmake with:
  qmake -set QMAKEFEATURES /path/to/this/dir

This works pretty nice except that QtCreator seems not to notice INCLUDEPATHs in C++ Editor so any #include with header from library added by prf are marked as "file not found" which results in not working code completion and lot of yellow highlighted lines as it can't resolve type names. But projects are compiling. Could it be made to parse also prf files? I checked in QtCreator sources and I found that prf files are parsed so shouldn't code completion and #include's work fine?