In GTK 3 Glass toolkit implementation function gdk_device_manager_get_client_pointer() is called in GtkEvent processing which is wrong usage according to documentation (https://developer.gnome.org/gdk3/stable/GdkDeviceManager.html#gdk-device-manager-get-client-pointer ):
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You should use this function seldomly, only in code that isn’t triggered by a GdkEvent and there aren’t other means to get a meaningful GdkDevice to operate on.
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