Yep, have just installed, and only trying to create a new file. All I have done is create a wall, then try to delete it.. Have tried the various options to delete - right-click menu, delete key, top menus - all give the same response (ie just appears to "unselect" the wall - not delete)
Running Opensuse Leap 42.1 x64.
Did have the issue with Preferences closing the app, but then ran the SweetHome3D-NoOffscreen link.
All keys and mouse work fine with every other app...
Not sure.