How to keep a running instance of geany 1.23.1 glued to a desktop?

How to keep a running instance of geany 1.23.1 glued to a desktop?

I am running Slackware linux and geany 1.23.1. I keep a running instance
of geany open in virtual desktop #3 and use the other desktops for other
work. When I open a new file from an other desktop, it opens in the
running instance, BUT that instance then jumps to my current desktop. The
older geany 1.19 left the running instance in #3, and opened the new file.
How can I get 1.23.1 to do the same? I read the geany manual. Nada.