That worked just as normal but as soon as I left LXBeams to have a look at the new lamps different specified values in a pdf or a website I wasn't very welcome back...
I check my pdf to see that a tight beam angle is to be set to 12 degrees and then I return to LXBeams to enter that value...
But no. It's then impossible to add that value. The properties window that I left open is now locked and will no longer let me enter any values.
So I close and reopen it, and then it works as expected again. slightly annoying

Seems like some minor bug in LXBeams Version 6.0.3 (17729.1)