If you are using opera-qt4 and do not like the tray icon with the pale background (or just have a thing against tray icons) this is an easy way to get rid of it. Right click on the opera desktop icon then go to properties-application-command. In command, delete the current line and insert "opera-notrayicon" (without the quotes), close and no more icon. This will also work with the other opera in the repos. This tip comes without any warranty, express or implied. If this tip brings about any unusual behavior or causes your significant other to dump you, you're on your own.
ps. If you do not have a desktop icon, you could either find the config file, or right click on opera in main menu and choose edit item, you should see the option for command, insert the above line and save.