Version:           3.3.2 (using KDE KDE 3.5.2)
Installed from:    Ubuntu Packages
Compiler:          i486-linux-gnu 
OS:                Linux

Modifications of .pro file done by Kdevelop interfacecorrupts the .pro file when it contains scopes. In facts scope section is moved down.

Example of .pro file:

macx{
  SOQTLIB += $$system(soqt-config --ldflags)
}
win32{
  SOQTLIB += X:\Coin3D\lib\soqt1.lib \
             X:\Coin3D\lib\coin2.lib
}
unix{
  SOQTLIB += -L/usr/local/lib -lSoQt \
             -L/usr/lib -lCoin
}

LIBS += $$SOQTLIB

HEADERS += ...
SOURCES += ...

After adding a class with "Project-> New Class..." the .pro file is corrupted because the platform dependent part (scopes) is pushed down:

HEADERS += ...
SOURCES += ...

LIBS += $$SOQTLIB

macx{
  SOQTLIB += $$system(soqt-config --ldflags)
}
win32{
  SOQTLIB += X:\Coin3D\lib\soqt1.lib \
             X:\Coin3D\lib\coin2.lib
}
unix{
  SOQTLIB += -L/usr/local/lib -lSoQt \
             -L/usr/lib -lCoin
}

Thanks for suggesting at least a work around.