Thanks @BHAYT , we had discussed this in another post already: Integration and compitability of PL6 and FastRawViewer for culling and rating - DxO PhotoLab - DxO Forums.
I am using digikam, which uses the internal Windows “open with” dialog, which unfortunately does not work as an “external selection”. It is the same as opening an image from the windows explorer. However, I am positive that this will be adjusted soon.
@John-M it will only point to the same folder of the last shutdown when you start the PL program directly. But if you double click on an image in the Windows Explorer, or open an image with the “Open With” command, it will open the folder of that image in the Photolibrary module. I was hoping that could be changed to open in customized mode. But as I have found out now, this can be achieved, if you open the image from the command line and pass the absolute image path (or several) as parameter. I just wish, it would also work like that directly from Windows.