About Box
This is just the application's about box :)
Main interface
This is FastIcns' main interface: a simple rotating cube showing on your desktop.
Image in the box
You see the dropped image in the rotating cube to show it's the current one.
Save Dialog
Double-click on the cube or Cmd-S or File -> Save to get to the Save dialog, where you can choose the target file's name and format.
Save to dropped file
Drop a file or folder on the cube holding the Command key to set the icon for that file or folder to the current image. It's the same as choosing "resource fork" as the save format: the content of the file remains untouched.
Saved files
The file cinq.icns was saved double-clicking and choosing the ICNS format.
The file cinq was saved in the "resource fork" format (it's a 0-bytes file with an icon).
The file cinq.jpg was dropped on the cube holding the Command key to set the icon of the file.
Face color
You can change the color of the cube's faces from the menu Edit -> "Set Face Color" (or Cmd-F).
No-cube interface
You can choose to view the image plain and simple, no rotating cube. The image is framed to better understand the limits. The bordered gray background appears when the mouse is over the window (cube or no cube - it can be disabled).