OverlayCanvas.ShowPopup

Отображает накладку в виде всплывающего окна в EditorWindow.

using UnityEditor;
using UnityEditor.Overlays;
using UnityEditor.ShortcutManagement;
using UnityEngine;
using UnityEngine.UIElements;

class PopUpOnlyOverlay : Overlay
{
    public PopUpOnlyOverlay()
    {
        displayName = "Pop Me Up";
    }

    public override VisualElement CreatePanelContent()
    {
        return new Label("I'm a pop-up overlay!");
    }

    [Shortcut("PopUpOnlyOverlayExample/Pop Up Overlay",typeof(SceneView), KeyCode.P, ShortcutModifiers.Shift)]
    static void ShowOverlay(ShortcutArguments args)
    {
        var window = args.context as EditorWindow;
        if (window is ISupportsOverlays)
            window.overlayCanvas.ShowPopup<PopUpOnlyOverlay>();
    }
}
.