/usr/include/libdtk-2.0.7/ is in libdtkcore-dev 2.0.7.1-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libdtk-2.0.7/DCore/
/usr/include/libdtk-2.0.7/DCore/AbstractAppender.h
/usr/include/libdtk-2.0.7/DCore/AbstractStringAppender.h
/usr/include/libdtk-2.0.7/DCore/ConsoleAppender.h
/usr/include/libdtk-2.0.7/DCore/CuteLogger_global.h
/usr/include/libdtk-2.0.7/DCore/DBaseFileWatcher
/usr/include/libdtk-2.0.7/DCore/DFileSystemWatcher
/usr/include/libdtk-2.0.7/DCore/DFileWatcher
/usr/include/libdtk-2.0.7/DCore/DFileWatcherManager
/usr/include/libdtk-2.0.7/DCore/DLog
/usr/include/libdtk-2.0.7/DCore/DObject
/usr/include/libdtk-2.0.7/DCore/DObjectPrivate
/usr/include/libdtk-2.0.7/DCore/DPathBuf
/usr/include/libdtk-2.0.7/DCore/DPinyin
/usr/include/libdtk-2.0.7/DCore/DSettings
/usr/include/libdtk-2.0.7/DCore/DSettingsGroup
/usr/include/libdtk-2.0.7/DCore/DSettingsOption
/usr/include/libdtk-2.0.7/DCore/DSingleton
/usr/include/libdtk-2.0.7/DCore/DStandardPaths
/usr/include/libdtk-2.0.7/DCore/DUtil
/usr/include/libdtk-2.0.7/DCore/DtkCore
/usr/include/libdtk-2.0.7/DCore/FileAppender.h
/usr/include/libdtk-2.0.7/DCore/LogManager.h
/usr/include/libdtk-2.0.7/DCore/Logger.h
/usr/include/libdtk-2.0.7/DCore/OutputDebugAppender.h
/usr/include/libdtk-2.0.7/DCore/RollingFileAppender.h
/usr/include/libdtk-2.0.7/DCore/dabstractunitformatter.h
/usr/include/libdtk-2.0.7/DCore/dbasefilewatcher.h
/usr/include/libdtk-2.0.7/DCore/ddisksizeformatter.h
/usr/include/libdtk-2.0.7/DCore/dfilesystemwatcher.h
/usr/include/libdtk-2.0.7/DCore/dfilewatcher.h
/usr/include/libdtk-2.0.7/DCore/dfilewatchermanager.h
/usr/include/libdtk-2.0.7/DCore/dobject.h
/usr/include/libdtk-2.0.7/DCore/dobject_p.h
/usr/include/libdtk-2.0.7/DCore/dpathbuf.h
/usr/include/libdtk-2.0.7/DCore/dpinyin.h
/usr/include/libdtk-2.0.7/DCore/dsettings.h
/usr/include/libdtk-2.0.7/DCore/dsettingsbackend.h
/usr/include/libdtk-2.0.7/DCore/dsettingsgroup.h
/usr/include/libdtk-2.0.7/DCore/dsettingsoption.h
/usr/include/libdtk-2.0.7/DCore/dsingleton.h
/usr/include/libdtk-2.0.7/DCore/dstandardpaths.h
/usr/include/libdtk-2.0.7/DCore/dtimeunitformatter.h
/usr/include/libdtk-2.0.7/DCore/dtkcore_config.h
/usr/include/libdtk-2.0.7/DCore/dtkcore_global.h
/usr/include/libdtk-2.0.7/DCore/dutil.h
/usr/include/libdtk-2.0.7/DCore/gsettingsbackend.h
/usr/include/libdtk-2.0.7/DCore/qsettingbackend.h