In Ubuntu 12.04, we need to whitelist application to show in systray, but Ubuntu 14.04 removed the systray whitelist settings from DConf. This caused issues for applications like xchat, parcellite etc.
Even though I found lot of solution while googleing, the only one worked for ubuntu 14.04 is,
sudo apt-add-repository ppa:gurqn/systray-trusty sudo apt-get update sudo apt-get upgrade
If you don’t want to update the whole packages, you can try installing only the following ones,
sudo apt-get install libunity-core-6.0-9 unity unity-services
After installing you need to either logout and login or restart your computer. Now the applications likes xchat can be easily minimized to system tray and open when ever you want.