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On windows, it works as expected. Resize border is removed and maximise button is disabled, but on Mac this is not working. Resize border is available and maximise button is enabled.
According the docs you can consider to use SetWindowStyleFlag and read the note below from documenetaion:
Please note that some styles cannot be changed after the window creation and that Refresh() might need to be called after changing the others for the change to take place immediately.
SetWindowStyle is a just wrapper over SetWindowStyleFlag.
"Please note that some styles cannot be changed after the window creation and that Refresh() might need to be called after changing the others for the change to take place immediately."
I am not a user of Mac, but I can try to suggest note form docs about Refresh():
Note that repainting doesn't happen immediately but only during the next event loop iteration, if you need to update the window immediately you should use Update() instead.