I believe it is still an issue with dash to dock extension (or possibly another one but in my case I only run 4 extensions and dash to dock is the only one that modifies the desktop behavior). For me I ran the following commands and I haven’t been able to get it to cause the issue again. (As a side note so you don’t have to reboot your system if it does occur again you can switch to a different TTY (CTRL-ALT-F3) for example log in and run this command to get control of your desktop back.
Type the following to disable the extensions to at least allow me to get back into my system without having to restart after activities hijacks the system.
gsettings set org.gnome.shell disable-user-extensions true
Then you can either re-enable them either through the extensions app or using the following command:
gsettings set org.gnome.shell disable-user-extensions false
Here is a link to my original post about this as for me it occurred during the last update. I’m not sure what has changed on my system other than running the above commands on my system but I haven’t been able to get the activities to “hijack” my system anymore.