Java applet can't open files under Safari 7 (Mac OS X 10.9)
I had a similar problem with another Java app today. I think you may need to add your app to the "Allow the apps below ..." list in this dialog (System Prefs -> Security & Privacy -> Accessibility):
For Safari 11:
- go to Safari Preferences->Websites->Plug-ins, and select Java
- at the right side you can see list of 'Allow websites to use this plug-in with settings below'
- now select the website
- press and hold Option button and then click the three option (Ask, Off, On), you will see additional option 'Run in safe mode' - un-check this option.
