Fix compilation of snippet and code style
Also the snippets appear to be using kdelibs4support, which is sth. we should adjust.
But one step at the time ;)
In regards to the second commit the docs at https://api.kde.org/frameworks/kconfig/html/classKConfigGroup.html explicitly state:
readEntry("...", Qt::white) will not compile because Qt::white is an enum. You must turn it into readEntry("...", QColor(Qt::white)).