Greeting Philippe, sorry I do not speak French (Tough enough to do English correct, so google will have to translate.)

"Hello, Simple question, Do you foreseea development versionfor mobile?It is intune with the timesandI'm interested.thank youPhilippe"

There has been several posting about mobile and responsive design.  Search mobile and you will find several postings.  And all the websites I checked made with X5 worked fine with the iphone 4s.

Good Luck! Donald

Ilaeu plusieursaffichagesurles terminaux mobilesetsensibles.Recherchermobile etvous trouverez plusieursoffres.Ettous les sitesque j'ai vérifiéà base deX5a bien fonctionnéavec lesiphone 4s.

Bonne chance!Donald