My packages for 'testing' are up-to-date as they are updated everyday via aptitude.
However I absolutely have no chance - for weeks already - to recompile a recent kernel, be it from DEB or directly from www.kernel.org, via the method "make xconfig". Always the same complaint (abbreviated): no QT4, searching for QT3, no qmake found, aborting.
Well I have several times over the weeks reinstalled all QT-files, that seemed to be of ANY relevance to the system, but no chance to get a "xconfig" running. Oh and "qmake" resides in /usr/bin from the beginning on! Mode 100755, no trouble to be read by everyone I think.
"Make menuconfig" runs flawlessly but I don't like that method very much.
Has anyone of you a faint idea, what these debian-purism-freaks now again have contorted in the packages to satisfy their glorious vision without taking into account, that ordinary people sometimes want to walk their own way? OR are programmers who within a whisp can discern and then alter these deviances.

Thanks.

Has nothing to do with Debian visions, but with how packages in Debian are handled. You need the development packages, those with the suffix -dev. If I am not wrong the error message you get should specifically ask for the Qt development packages. Install those and you should be fine.

Yes, you are absolutely right with your observation, that xconfig aks for "development"-files.
That's why I stated in capitals 'ANY relevance'. I had installed and reinstalled via aptitude following:
*qt4-dev-tools*
*qt4-qmake*
*libqt4-dev*
*libqt4-qt3support*
More *-dev files seemed to me to be of no relevance (libpoppler-qt4-dev only to name as an example).
Even *qconfig.h* - another file admonished - is on my system, but seemingly not in the environment, where xconfig expects it to be.
Do you have more hints, where a non-programmer can influence this weird behaviour?

Thanks.