Quick tutorial: How to add to the custom menu of an editor window

[Xarbrough]

Edit from the year 2022: People still find this thread regularly, take note that this feature is officially documented starting with Unity 2018: Unity - Scripting API: IHasCustomMenu

I’ve been wondering if I could add my own content to the custom menu that is built into every editor window. I’m still not sure, how that dropdown menu is called, but this is the one I mean:

Luckily, today I stumbled across the solution and wanted to share it since I couldn’t find much about it online.

using UnityEngine;
using UnityEditor;

public class MyWindow : EditorWindow, IHasCustomMenu
{
    [MenuItem("Window/MyWindow")]
    private static void ShowWindow()
    {
        GetWindow<MyWindow>().Show();
    }

    // This interface implementation is automatically called by Unity.
    void IHasCustomMenu.AddItemsToMenu(GenericMenu menu)
    {
        GUIContent content = new GUIContent("My Custom Entry");
        menu.AddItem(content, false, MyCallback);
    }

    private void MyCallback()
    {
        Debug.Log("My Callback was called.");
    }
}

To add your own custom entries, just add the IHasCustomMenu interface from the UnityEditor namespace to your EditorWindow class and implement it as shown in the sample.

You can, of course just do this:

public void AddItemsToMenu(GenericMenu menu)
{
    // ...
}

but I prefer the explicit interface because this method is one of those, which should only be called by Unity, not by my own code and the explicit declaration reminds me of the fact.

And finally, how did I find this functionality (since it is not mentioned in the Manual or the Scripting API)? I’ve looked at the decompiled UnityEditor.dll (the C# side of the engine, mostly concerned with the Editor API for drawing windows) and searched for the string “Stack Trace Logging” because I wondered how the Console window implemented this functionality and if I could add my own entries next to it.

Disclaimer: The IHasCustomMenu is not documented and so it is not officially supported and may not even work as I advertise. Additionally, it is not allowed to decompile Unity code, but there are some sources online which indicate, that the Unity staff is mostly ok with looking at editor code for educational purposes like this one.

Edit: Please, if anyone knows, tell me how this built-in custom menu is called and maybe I can update the title to make it more obvious that I’m not talking about user-generated custom menus.

[shawn_1]

Good tutorial! Your understanding of IHasCustomMenu is correct. It’s on our todo-list to add proper API for this, but just hasn’t happened yet.

@Xarbrough_1

Disclaimer: The IHasCustomMenu is not documented and so it is not officially supported and may not even work as I advertise. Additionally, it is not allowed to decompile Unity code, but there are some sources online which indicate, that the Unity staff is mostly ok with looking at editor code for educational purposes like this one.

Yep, good disclaimer. With that said, it’s perfectly fine to decompile Unity’s managed code.
From https://unity3d.com/legal/terms-of-service/software

Accordingly, you agree not to disassemble, decompile or reverse engineer the Unity Software, in whole or in part, or permit or authorize a third party to do so, except to the extent such activities are expressly permitted by this Agreement or by law notwithstanding this prohibition. Notwithstanding the restriction prohibiting decompiling in the immediately preceding sentence, you may decompile the Unity Common Language Infrastructure (CLI) assemblies solely to inspect their functionality for purposes of understanding or improving performance of Your Project Content or any editor extension to the Unity Software.

@Xarbrough_1

Edit: Please, if anyone knows, tell me how this built-in custom menu is called and maybe I can update the title to make it more obvious that I’m not talking about user-generated custom menus.

We just call it the EditorWindow’s Context Menu. Though it doesn’t really have an official name until there’s proper API for it.

[Xarbrough]

Thanks for the response! I do like the way custom extensions are handled with the Context Menu, would be nice to see more of this type of open design.

And thanks for linking those service terms, I didn’t know that there was an official statement about decompiling editor code.

[tcz8]

@Xarbrough_1 man… I don’t have the words to express how HAPPY I am to have found this. I just spent a week learning relfection (had never touched it) trying to figure out how to control the docking of windows and tab positioning… finaly got it to work but man the learning curve!

I can finally have a headache free day!

Thank you so much for posting your code

EDIT: Correction, I can have half a day headache free. Now I gotta figure how to remove something from that menu You wouldn’t happen to know were the generic menu of an editor window is stored?

[Xarbrough]

@tcz8

Now I gotta figure how to remove something from that menu

Glad I could help. Do you want to remove entries, which you added yourself to the menu or do you want to remove builtin entries added by Unity? I believe the latter case is rather difficult to change. It looks like all entries are added by Unity in place before the window is displayed and the data is not retained, so cannot be changed without changing the actual Unity source code, but maybe I’m wrong.

[nehvaleem]

awesome! thank you ^^