Where to put common writable application files?

Question

I thought that CSIDL_COMMON_APPDATA\\company\\product should be the place to put files that are common for all users of the application and that the application

Answer 1

Modify just the security on a specific sub-directory of the AppData directory (this is from the link you provided):

CSIDL_COMMON_APPDATA This folder should be used for application data that is not user specific. For example, an application may store a spell check dictionary, a database of clip-art or a log file in the CSIDL_COMMON_APPDATA folder. This information will not roam and is available to anyone using the computer. By default, this location is read-only for normal (non-admin, non-power) Users. If an application requires normal Users to have write access to an application specific subdirectory of CSIDL_COMMON_APPDATA, then the application must explicitly modify the security on that sub-directory during application setup. The modified security must be documented in the Vendor Questionnaire.