Private Browsing with Safari

[claudiobosticco]

SmartClient Version: v9.0p_2013-12-03/PowerEdition Deployment (built 2013-12-03)

I've just discovered that Safari in Private Browsing mode gives an error when trying to use local storage (via isc.Offline.put() method):

15:52:13.864:XRP1:WARN:Log:Error: QuotaExceededError: DOM Exception 22
Stack from error.stack:
setItem@[native code]
$788@https://srvubuntu.juventus.priv:8443/Jta/isomorphic/system/modules/ISC_DataBinding.js?isc_version=v90p_2013-12-03.js:1707:343
put@https://srvubuntu.juventus.priv:8443/Jta/isomorphic/system/modules/ISC_DataBinding.js?isc_version=v90p_2013-12-03.js:1704:156

is there available a workaround? At least, is it possible to know if the local storage is not available?