My wish: I want kdenlive to save everything of a project into one folder, wich I can create where I want it. Now my computer is filled with several folders named ladspa, thumbs and titles and the files projectname.kdenlive.

eg: I have a folder DV. In this folder there are several directories with the material of serveral projects sun, flowers and animals. If I work with the project sun, I want this directory-structure:

~/DV/sun/kdenlive/ladspa/files
~/DV/sun/kdenlive/thumbs/files
~/DV/sun/kdenlive/titles/files
~/DV/sun/kdenlive/sun.kdenlive

and with the project flowers:

~/DV/flowers/ladspa/files and so on

kdenlive should ask on startup, if to open an existing project or create a new one.

Best regards

Hartmut

In the settings dialog under Environment -> Default folders you can set up a default project folder.
And when you create a new project you can choose another one. The folders you named should then be in this folder.