When used in i3 window manager, the panel overlaps ordinary windows. I referred to the documentation at http://i3wm.org/docs/wsbar.html, which said that "When a program sets the appropriate hint (_NET_WM_WINDOW_TYPE_DOCK), it will be managed in dock mode by i3."
In the fbpanel configuration, I have already selected "Set 'Dock' type". Even then, this seems to have no effect in i3.
Can you please set this hint?