The html5 client is client and not server and has zero influence on rdp session side, you see only picture as human of what is going on there, html5 client self is not aware what is going on inside rdp session, if you press logoff button or not, it has zero feedback about except that connection was closed and the reason why if it was sent. But RemoteApp works in remoteapp mode and I assume for html5 client in new TSplus version on rdp session side are attached different rules which probably hinder the session to logoff properly. I don't know which rules that are, i did not develop server side, but on html5 client side there were made no changes regarding that option to make it working differently than before. On my side the issue is not reproducable even with latest version so i can't tell you anything useful about, let also the developers check the things.
HTML5 Clients doesnt logoff
Re: HTML5 Clients doesnt logoff
TSplus HTML5 and Java web engineer