This is what happens. The Open section of the Ribbon is disabled/greyed out as soon as I add a new file in the midst of a project. This does not happen when I add several files AT ONCE at the beginning of a new project. The next thing I have to do is go back to the list of Projects, set ANOTHER Project as active and then make the current Project once again active. Apparently that does the trick. I believe this shouldn't happen. Does anybodoy know why? Not to mention, that sometimes, once you make your active Project active again (as mentioned above) the file you had added is no longer there and then when you try to add it again the system tells you that the file is already added... This is plain nonsense to me. Thanks for any hints.