my Addition to that topic would be the following possible solution:

A node that reads a ".cginc" file and presents a dropdown to import a specific function. The node should generate the input vars from the function definition and the rest can act like the code-node!?

arr duplicated :)

http://shaderforge.userecho.com/topic/461621-it-should-be-possible-to-incorporate-stuff-from-custom-cginc-includes-in-code-blocks/

using UnityEngine;
using UnityEditor;

public class ExampleEditor : EditorWindow {
    string fieldValue = "Some Value";
    Vector2 scrollPosition = Vector2.zero;
    [MenuItem ("Window/My Window")]
    public static void  ShowWindow () {
        EditorWindow.GetWindow(typeof(ExampleEditor));
    }
    void OnGUI () {    
        // Fetch the text area style from the current GUI skin
        GUIStyle textAreaStyle = GUI.skin.textArea;
        // Change some definitions
        textAreaStyle.richText = true;
        textAreaStyle.padding.left = 10;
        textAreaStyle.padding.top = 10;
        textAreaStyle.padding.right = 10;
        textAreaStyle.padding.bottom = 10;
        textAreaStyle.stretchHeight = true;
        // Create a space for the text area
        Rect bounds = new Rect(5, 10, Screen.width - 10, Screen.height - 40);
        // Define a scrollable area
        GUILayout.BeginArea(bounds);
        scrollPosition = GUILayout.BeginScrollView(scrollPosition);
        // Add the text area
        fieldValue = EditorGUILayout.TextArea (fieldValue, 
                                               textAreaStyle,
                                               GUILayout.MinWidth(bounds.width - 30 ),
                                               GUILayout.MaxHeight(bounds.height));
        GUILayout.EndScrollView();
        GUILayout.EndArea();
    }
}