I would like to put a set of radio buttons and checkboxes inside a Native.Alert() but I can’t seem to find a way to do so. In my app I want the user to be able to pick from a set of files and choose a particular one from the server to load. However, I cant find a way to make a list or clickable menu or radio button. How would you approach that. Any help would be appreciated! Thank you!
You can’t add corona objects to native objects.
Also, unfortunately, there is no way to add a radio button to an alert. Alerts are basic interaction dialogs.
You’ll have to make your own dialog lib/module to do this.
On the positive side, it is possible to make sexy/beautiful dialogs Corona SDK/Solar 2D.
Download my game and see the options dialog: https://play.google.com/store/apps/details?id=com.roaminggamer.cwp
PS - This game was an experiment and I learned some very important things.
Biggest Takeaway - If you make a game like a much loved game (Wordscapes) and do anything wrong…you will get whacked by reviewers. 
Last reply I promise.
SSK2 provides an easy way to create dialogs w/ your own art. This is the same feature used in my game.
https://roaminggamer.github.io/RGDocs/pages/SSK2/libraries/dialogs/#custom-trays
Note: My verification suite has a test for this feature, but I need to fix the test. So, if you run the SSK validation suite be aware of that.