Allow sorting of files listing and support drag and drop

[wyatt-wong]

i found that in the selection of the IiGS ROM file and selection of files for the hard disk or floppy disk from the hard disk and floppy disk icon, the display file file listing did NOT allow sorting, so I have to go through a list to locate the folder in order to find the IIGS ROM file, or to go through a list of games to choose the game I want to startup.

Furthermore the hard disk and floppy disk icon did NOT support drag and drop. I could not simply dragged a file into the hard disk or floppy disk icon.

I would suggest to use the NATIVE Windows, macOS and Linux file selection dialog box which automatically offer the function to sort filename, file size, modification time, etc. instead of building your own file selection dialog box in the macOS environment.