KConfig
Widgets for configuration dialogs.
KConfigWidgets provides easy-to-use classes to create configuration dialogs, as well as a set of widgets which uses KConfig to store their settings.
Using the Module
Using a Qt module's C++ API requires linking against the module library, either directly or through other dependencies. Several build tools have dedicated support for this, including CMake and qmake.
Building with CMake
Use the find_package() command to locate the needed module component in the Qt6 package:
find_package(Qt6 REQUIRED COMPONENTS KF6)
target_link_libraries(mytarget PRIVATE Qt6::KF6)
For more details, see the Build with CMake overview.