Hello Simon and welcome to the Advanced Installer Forum
You can do what you wish quite easily.
Simply go to the
Dialogs page and create a new dialog from the ribbon --> "New Dialog" (RegistryDlg) or select an existing one.
Click on the "Controls Toolbox" that is located on the ribbon as well and from there add a Edit Box. Let's set it's Property Name to DATABASE_PROP_REG.
In order to store the information provided by the user, go to the
Registry page. Here you can click on the "New Value" (Value Database)
from the ribbon and the
Edit Registry entry dialog will pop up. In the data field insert the [DATABASE_PROP_REG] property. You can also take a look on the
Add registry keys and values to your package article with related information for hints and guidance.
I have included a sample project detailing this.
Regards,
Dan