Open a file with the associated program with left double click

I want to open a psd file with a simple left double click in Photoshop.
After searching for a while to fullfill this simple task, I found that I had to change the behaviour via the filetype settings.
As it worked out of the box with a pdf file I used this as template and configured the psd filetype like this:

It opened Photoshop but not with the selected file. After searching and searching and searching again, I found that I obviously had to create an event (Left doubleclick) to make this working and indeed it worked.
Strange thing for me: no such event exists for the pdf filetype. Why?
And is DO really so complex and needs so many actions to perform such a simple task?
And btw. the help is not really helpfull, as the screenshots there do not reflect what I see in the software. And searching for something like "open file with" doesnt also give me usefull results.

Windows' Open with dialog should be all you need.

What happens if you doubleclick a psd file in Windows Explorer? Usually it's Windows that handles file associations, not DOpus. There should be something like "Default Apps" in Windows where you can change these settings.

In Windows Explorer it behaves as it should. Double clicking on a file opens it with the associated program. And Photoshop is set as standard for psd files. Works everywhere else, but not in DO.