https://discussions.unity.com/t/can-i-open-editorwindow-from-custominspector/7484
Can I open EditorWindow from CustomInspector ? - Questions & Answers - Unity Discussions
Sep 15, 2010 - When I try to open EditorWindow from CustomInspector, I have such errors : NullReferenceException: Object reference not set to an instance of an object...
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