[Mono-osx] NSWorkspace.SharedWorkspace.IconForFileType

[Pavel Sich]

Function NSWorkspace.SharedWorkspace.IconForFileType seems not working. 
Always returns the default image (empty file) and not the system icon as 
expected.

Call it with the params like "root", "desk" or "FNDR" which are return 
values for function of:
NSFileTypeForHFSTypeCode(kComputerIcon);
NSFileTypeForHFSTypeCode(kDesktopIcon);
NSFileTypeForHFSTypeCode(kFinderIcon);

usually used in ObjC in combination of iconForFileType selector.

Cheers,
Pavel
@sichy