We’re improving the way in-page localization works in Pontoon by droping a feature instead of introducing a new one. Translating text on the web page itself using the contentEditable attribute has been turned off.

That means the actual translation (typing) always takes place in the translation editor, which gives you access to all the relevant information you need for the translation.

The sidebar is always visible, allowing you to select strings from the list and then translate them. Additionally, you can still use the Inspector-like tool to select any localizable string on the page, which will then open in the translation editor in the sidebar to be translated.

Translation within the web page has turned out to be suboptimal for various reasons:

• Original string is not always presented unambiguously, e.g. if containing markup,
• Additional string details like comments and file paths are not displayed,
• Suggestions from history, machinery and other locales are not available,
• Only the first plural form can be translated,
• It’s hard to control markup or new lines on various sites if they’re part of the string.

http://horv.at/blog/improving-in-page-localization-in-pontoon/