I use KDevelop version 5.2.1 that comes with the current LTS of Xubuntu.

I like to import a CMakeLists.txt file. But in the Open/Import Project file browser has it simply greyed out. Do I miss some dependencies to get support for that? Or does this specific KDevelop version has no import for that? My google-fo did not help me so far to find anything related.

Never mind... just have to select the directory that contains the CMakeLists.txt now.

Yeah. This is because some platforms do not support file dialogs for "select either a file or a directory", which would be required here.