How to display red text in inspector widow with editor class? like an error or warning

Unity Editor Interface
1

I imported a ttf,but the material is readonly,

        GUIStyle style = new GUIStyle();
        style.font = editorFont;
        editorFont.material.color = Color.red;
        GUILayout.Label(str,style);

the code above is useless. texts are still black…

2 
editorFont.material.SetColor("_TextColor",Color.red);

is also useless

3