Cocoa’s Broken Proxy Icons
Apple is abundantly clear on how a proxy icon should behave. In a Carbon dev doc titled “Handling Carbon Windows and Controls: Basic Window Manipulation,” Apple says in a section called “Adding Window Proxy Icons”:
If you create a document window, you should add a proxy icon to the title bar. This icon, which appears next to the window’s title, serves as a proxy for the document’s icon in the Finder. This proxy icon should appear and behave the way the document’s icon does in the Finder.
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In Cocoa applications, aliases are created at the drop locations—even across disks where a copy occurs in the Finder. When dragging proxy icons to the trash, nothing at all is done in Cocoa apps.