I recently upgraded my workstation to Ubuntu 20.04 and have a small annoyance with x2go client app: the icon for the remote desktop window (X2GoAgent) doesn't appear in the dock. It's just a blank square. If I alt-tab, it shows the mini-window, but also no icon where I'd expect in the lower right corner.
Setting a custom icon also doesn't work.
Image here: https://i.stack.imgur.com/0p4mn.png