Description of problem:
When I open any menu from system tray in LXDE (for example, by right clicking on network connection), all Openbox hotkeys don't work. I've found it when tried to make a screenshot of Dropbox tray menu by binding scrot to Print Screen key. It works when menu is not open, but it doesn't when menu is open. All other Openbox hotkeys (like Super+E that launch pcmanfm) also don't work when any tray menu is open.
I think this may be one of the X11 limitations. When a menu grabs the input, no other client will receive the input.
Does it work with other window managers?
I don't have other window managers, so I can't test it.
Ok, I'm closing this as CANTFIX. If you think it's not a X11 limitation and can't reproduce it with another window manager, please reopen.