UnitySerializedReferenceUI/DefaultUI/SerializeReferenceInspectorButton.cs

#if UNITY_EDITOR

using System;
using System.Collections.Generic; 
using UnityEditor;
using UnityEngine;

public static class SerializeReferenceInspectorButton
{
    public static readonly Color SerializedReferenceMenuBackgroundColor = new Color(0.1f, 0.55f, 0.9f, 1f);

    /// Must be drawn before DefaultProperty in order to receive input
    public static void DrawSelectionButtonForManagedReference(this SerializedProperty property,  Rect position, IEnumerable<Func<Type, bool>> filters = null) =>  
        property.DrawSelectionButtonForManagedReference(position, SerializedReferenceMenuBackgroundColor, filters);
    
    /// Must be drawn before DefaultProperty in order to receive input
    public static void DrawSelectionButtonForManagedReference(this SerializedProperty property, 
        Rect position, Color color, IEnumerable<Func<Type, bool>> filters = null)  
    { 
  
        var backgroundColor = color;   
            
        var buttonPosition = position;
        buttonPosition.x += EditorGUIUtility.labelWidth + 1 * EditorGUIUtility.standardVerticalSpacing;
        buttonPosition.width = position.width - EditorGUIUtility.labelWidth - 1 * EditorGUIUtility.standardVerticalSpacing;
        buttonPosition.height = EditorGUIUtility.singleLineHeight;

        var storedIndent = EditorGUI.indentLevel;
        EditorGUI.indentLevel = 0;
        var storedColor = GUI.backgroundColor;
        GUI.backgroundColor = backgroundColor; 
         
        
        var names = ManagedReferenceUtility.GetSplitNamesFromTypename(property.managedReferenceFullTypename);
        var className = string.IsNullOrEmpty(names.ClassName) ? "Null (Assign)" : names.ClassName;
        var assemblyName = names.AssemblyName;
        if (GUI.Button(buttonPosition, new GUIContent(className, className + "  ( "+ assemblyName +" )" )))
            property.ShowContextMenuForManagedReference(buttonPosition, filters);
        
        GUI.backgroundColor = storedColor;
        EditorGUI.indentLevel = storedIndent;
    }
}

#endif