Yes, Patchou implemented a work-around to set the window title without adding a Plus! title bar. When sending WM_SETTEXT, pass 1 as wParam. This parameter has no meaning for the Windows API, but when sent to a Plus! window, it'll prevent the title bar from being added.
js code:
Interop.Call("user32", "SendMessageW", pPlusWnd.Handle, WM_SETTEXT, 1, "New Window Title");
This has been around since Plus! 4.50.317, so normally you shouldn't have to worry too much about backwards-compatibility.
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