GameViewToolbar.cs

using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

public class GameViewToolbar
{
    static VisualElement toolbar;

    [MenuItem("Example/Add Toolbar")]
    public static void AddToolbar()
    {
        if (toolbar == null)
        {
            System.Reflection.Assembly assembly = typeof( UnityEditor.EditorWindow ).Assembly;
            System.Type type = assembly.GetType( "UnityEditor.GameView" );
            var gameView = EditorWindow.GetWindow(type);

            toolbar = new VisualElement();
            toolbar.style.flexDirection = FlexDirection.Row;
            toolbar.style.top = 22;

            toolbar.Add(new Button(() => Debug.Log("I was pressed")){ text = "Press Me 1" });
            toolbar.Add(new Button(() => Debug.Log("I was pressed")){ text = "Press Me 2" });
            toolbar.Add(new TextField("Some Text"){ value = "Hello world" });
            gameView.rootVisualElement.Add(toolbar);
        }

        toolbar.visible = true;
    }

    [MenuItem("Example/Hide Toolbar")]
    public static void HideToolbar()
    {
        if (toolbar != null)
            toolbar.visible = false;
    }
}

Adding custom elements to the GameView

This is really nice! Is there a nice way to make such a toolbar persistent; let it be saved by Unity as part of the Game View window? If not, it's probably easy to save an editor pref to know if the toolbar should be shown and then rebuild the static variable in InitializeOnLoad.

This is really nice! Is there a nice way to make such a toolbar persistent; let it be saved by Unity as part of the Game View window? If not, it's probably easy to save an editor pref to know if the toolbar should be shown and then rebuild the static variable in InitializeOnLoad.

At the moment this is not possible. This example is more of a hack taking advantage of the way UIElements works. Hopefully in the future custom toolbars will be supported in a nicer way that does persist. We actually use this in the localization package and do something similiar to checking a playerpref to determine if we should show the UI component. We also use InitializeOnLoad.