pb installation sur MAC

I have come across this issue in Mavericks with another downloaded app. I think it is another new form of protection from 'unkown' applications - those not from the app store. You can still open it by holding down the control key while clicking the app or disc image. Hope I have not translated this badly.

J'ai rencontré ce problème dans Mavericks avec une autre application téléchargée. Je pense que c'est une autre nouvelle forme de protection contre les applications «unkown» - ceux qui n'ont pas de l'App Store. Vous pouvez toujours ouvrir en maintenant enfoncée la touche Ctrl tout en cliquant sur l'image de l'application ou le disque. J'espère que je n'ai pas encore traduit ce mal.

This is Apple's "Gatekeeper" which blocks programs from being installed on your computer that isn't part of AppStore enviroment or their registered developers. I think it came in with Mountain Lion, I moved from Lion to Mavericks so had not seen it before.

Bypass Gatekeeper on a case-by-case basis - this is the method we recommend using. It gives you Gatekeeper's full security, but the flexibility to open occasional unsigned apps when you know and trust them.
If you attempt to open an app you downloaded from a source other than the Mac App Store, and get the popup, you'll need to override Gatekeeper in order to open it. As always, make sure you know where the app came from before overriding Gatekeeper.
Instead of double-clicking on the app in question to open it <Ctrl+click> or <right click> on the app and select Open from the contextual menu.