https://bugs.winehq.org/show_bug.cgi?id=40090
Ken Thomases ken@codeweavers.com changed:
What |Removed |Added ---------------------------------------------------------------------------- CC| |ken@codeweavers.com
--- Comment #1 from Ken Thomases ken@codeweavers.com --- This was a deliberate decision. I seem to recall that, at the time, the Human Interface Guidelines strongly discouraged the use of the document proxy icon in a window's title bar for anything other than, well, a proxy for a document that the window was presenting. The documentation has been overhauled and I can no longer find that, but I think the rationale is still sound.
The icon only shows up if you assign a URL of a document that the window is supposed to represent to the window. If you assign a URL, the window shows a pop-up menu for the path of the URL when you Control-click, Command-click, or right-click on the title. Also, the icon is draggable. The intent is to let the user drag the document file someplace, just as if he were dragging it from the Finder. There are delegate methods to suppress some of this behavior, but even with those implemented the icon still highlights briefly when you try to drag it.
In general, it's just a poor user experience. Mac users will expect that icon to represent a document, not the app. I don't think you'll find many other Mac apps which put an icon in their windows other than for documents.
If you want to turn off Mac window decorations when using the Mac driver, you can do that. Unlike with the X11 driver, it's not as simple as a switch in winecfg. You have to set a registry setting using regedit:
[HCKU\Software\Wine\Mac Driver] "Decorated"="n"