If your Improviser folder is empty please download the missing FLI song progression files from the following link and place them into the empty Improviser folder. Folder location: Macintosh HD/Users/(the name of your computer with a house icon)/Music/Fretlight/Improviser
If the Improviser's interface is not functioning or freezing or if the File>Open option is not allowing you to open the Improviser's FLI songs please complete the following steps.
Open a new Finder window by choosing "New Finder Window" from the File drop down menu. Once that is opened you will navigate in the window to the Improviser's song file folder by following this path.
Macintosh HD/Users/(the name of your computer with a house icon)/Music/Fretlight/Improviser
Once there, right click, or control click, anyone of the FLI song files, click on "Get Info", expand the "Open with:" section, click on the drop down menu and select "Other...", Change the "Enable:: drop down to "All Applications", check the "Always Open With" Box, select the Improviser and then click on the "Change All" button.
If you do not see the Improviser in the list of available applications open a new finder window, by choosing "New Finder Window" from the File drop down menu, go to the Applications folder, right clicking or control clicking on the Studio app, Click "Show Package Contents", open Contents folder, open Mac OS folder, drag and drop the "Fretlight Improviser.app" into the Applications folder on the side bar.
Important: To use your Improviser program you will have to double click a FLI file to open the Improviser, and then go back and double click the FLI file again to load it into the Improviser, and then press play to test it.