I think we could be able select a hidden files via "Files and Folders/Add Files...".
AI includes a hidden files too if are you using "Files and Folders/Add Folder...".
I'm afraid that I don't quite understand your request. Could you please provide a little more details?
Advanced Installer allows you to add hidden files to the project. If you are saying that they are not always displayed in the "Add Files..." dialog, it's because this dialog is created by Windows and it obeys the Windows settings.
Here is what you should do in order to display the hidden files and folders:
- Launch Windows Explorer.
- Select the "Tools/Folder Option" menu option.
- Select the "View" tab and check the "Show hidden files and folders" button.