Mac: tkinter_.py example: error with winfo_id() returning a negative value

[cztomczak]

Looks like there is no way to get window id (NSView pointer) in tkinter on Mac, so that browser can be embedded in that window. From tk manual:

winfo id window
Returns a hexadecimal string giving a low-level platform-specific identifier for window. On Unix platforms, this is the X window identifier. Under Windows, this is the Windows HWND. On the Macintosh the value has no meaning outside Tk.

Reference: https://www.tcl.tk/man/tcl8.4/TkCmd/winfo.htm#M17

Below is the error when trying to embed CEF browser using that negative window identifier:

[tkinter_.py] winfo_id()=-1683723760
Exception in Tkinter callback
Traceback (most recent call last):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1470, in __call__
    return self.func(*args)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 531, in callit
    func(*args)
  File "../examples/tkinter_.py", line 276, in embed_browser
    window_info.SetAsChild(self.winfo_id())
  File "thon/window_info.pyx", line 82, in cefpython_py27.WindowInfo.SetAsChild (cefpython.cpp:39561)
OverflowError: can't convert negative value to size_t

[cztomczak]

Fixed it by using PyObjC package to obtain NSView pointer:

    def get_window_handle(self):
        if self.winfo_id() > 0:
            return self.winfo_id()
        elif MAC:
            # On Mac window id is an invalid negative value (Issue #308).
            # This is kind of a dirty hack to get window handle using
            # PyObjC package. If you change structure of windows then you
            # need to do modifications here as well.
            # noinspection PyUnresolvedReferences
            from AppKit import NSApp
            # noinspection PyUnresolvedReferences
            import objc
            # Sometimes there is more than one window, when application
            # didn't close cleanly last time Python displays an NSAlert
            # window asking whether to Reopen that window.
            # noinspection PyUnresolvedReferences
            return objc.pyobjc_id(NSApp.windows()[-1].contentView())
        else:
            raise Exception("Couldn't obtain window handle")