After changing to Eclipse Oxygen 3 for my PHP work I have spent an hour to find out out what was wrong with the keyboard actions for navigating through code. One of the key combinations one typically needs is "Ctrl >" and "Ctrl <" to jump from one word to the other - more precisely between some whitespace/letter-combinations which are interpreted as word separation borders.
Whenever I restarted or reopened Oxygen3 the already opened editors on files I had worked with during the last session did not show any reaction to such key combinations. However, when I closed the file and reopened them again with the structured PHP-editor the key combination did work. But after a restart of the workspace no reaction again. It really took me a while to find out that all this was due to the "welcome" screen, which I had not deactivated, yet, in the new installation. After knowing this, I even did find a corresponsing bug and stack overflow report.
Just deeactivating the welcome screen did the trick. I find it very frustrating that this is really a rather old bug - and I could bet it cost a lot of people nerves and useless efforts.