No detection of screen size change in fullscreen when using xubuntu/xfce4 as host

[acathla]

With Ubuntu (Unity/metacity or compiz), no problem. With xfce4, I can resize the screen with xrandr or the xfce4 tools, vbox does not detect it. If I go windowed then fullscreen again (host + f), the vbox screen is resized correctly (and I see Display::handleDisplayResize() in logs). In case it's xfce's fault, is there a way to send the Display::handleDisplayResize() event manually?