I install xfce4 and xrdp in A container(ubuntu14.04),and install guacd and jetty in B container to proxy.
when I use Mac OS:
push Caps Lock for switching Lowercase to Uppercase,It work find.
when I push Caps Lock for switching Uppercase to Lowercase,It not work.
when I push Caps Lock and stay for two seconds，then it work
I check in Chrome DevTools Network-->ws,sometimes after I pushed Caps Lock,the websocket not push key to server.but sometimes if i push that button a few more times，websocket will push key to server over and over again.
what I have told above is for Mac os Chrome,Safari and Firefox，it will be worse in Windows Chrome and Firefox,I have to push for five seconds or even longer for switching Uppercase with Lowercase
I guess that changing input method may confused case switching,so I tried on the Ubuntu Chrome \ Firefox,and the problem show up again.
all of those in never show up in vnc,and everything goes find when I use brower to view the website in a container which connect by vnc