I finally did it!
I opened the "sample" file and deleted all walls and interriour. Then I wanted to delete the "background" picture - editting was possible, but no opening of a new one. So I deleted the background file...
Tried to "open" a new file - tada! "Open" dialog appeared, and from that time ...

Correct, when I do not open an existing document, the changed will be saved (manually or by clicking "save" on closing), it is not possible to open or save-as, the window to choose a file/filename does not appear.

I tried to use the command "SweetHome3D.exe -log MyLogFile.log", first time the file was created writing "system could not find the file" (in german ), another try and the system did not even create this file...

I downloaded the file, opened it by double-clickin, changed something and hit "save". That did actually work!
"open" or "save-as" still does not work, but the changes I did were saved.

Dear Puybaret,

thanks for the reply! I checked the setting, but my "Windows Security" is disabled though I use Norton 360.
I checked the settings of this Application aswell, but even disabling the full package and looking at the detailed history does neither give any useful information nor make ...

Dear all,

I downloaded version 7.0.2 and installed it. I use windows 11 (updated frequently), Java is also up-to-date. I can work with the software without any problem, also added some libraries from github. I've been working with the software some years ago. No issue so far, but as soon as I try ...