I am sorry to be the one to ask, as it seems all the other commenters know it already. I even searched internet for "What are XDG desktip portals", but this cam

I am sorry to be the one to ask, as it seems all the other commenters know it already. I even searched internet for "What are XDG desktip portals", but this came up with results for project that seem to use these portals, but no fast explanation of what they are? Can please somebody summarize what this is about? Disclaimer: I am a Linux user since >20 years, using XMonad window manager on Ubuntu 16.04 at the moment.