make compose panel managed by activity manager, there is a problem here that whether the hidden view will be lazy loaded regarding the code split mechnism

git-svn-id: https://svn.apache.org/repos/asf/james/hupa/trunk@1522295 13f79535-47bb-0310-9956-ffa450edef68
temporarily hide the left panel under composing, since the contact panel should be realized later

git-svn-id: https://svn.apache.org/repos/asf/james/hupa/trunk@1522296 13f79535-47bb-0310-9956-ffa450edef68