I'd like to make a cross platform file browser. What language / toolkit would you guys recommend? I'd like the app to be able to access details like security settings and metadata for files as well as be able to look into bundles on OS X. Will Java 7 / Swing be able to do this? Can I do it in Python (what GUI toolkit would you recommend?) I have a prototype of what I want already done in Obj-C / Cocoa, but people have suggested that it could be really successful if I make it cross platform instead. The UI is not very standard - I have too many ideas that are too central to the app and very different from anything you've ever seem before, so I'm going to end up with custom draw routines that make the UI look mostly the same regardless of which platform it's on.