I gave up. The task looked simple:
I have a list with clients with 2 columns: clientname, clientid, URL. I made another list where managers could collect clients from this list that they frequently visit, so they have it at hand all the time, regardless where they are browsing from.
So, made a lookup column in the new list, and wanted to show the customer name and also show the URL. But the URL column is just not there. I can add the URL's as plain text in another column and pull it with the lookup field, but of course, it is not a hyperlink anymore.
I tried it another way:
Pick the clientid and generate the url in a calculated column. But the additionally presented columns are not available for calculations.
So, the question is:
How could I fulfill this simple looking task: In a list, select the name of the customer from another list, add it to a field, and the same time, add the customer url too?