Where is task manager / task switcher configuration stored in a system with LXQT + Openbox?
I found the solution for my problem. In the keys binding configuration file (now in ~/.config/openbox/lxqt-rc.xml) the combination config for switching between windows is A-Tab. That's right, but there's also an option called <allDesktops>. In my case it said yes, I changed it to no and now it shows only windows from the current desktop.