EditorApplication.timeSinceStartup  

static var timeSinceStartup : double

Description

The time since the editor was started (Read Only)

This property contains the time since the editor was started, in seconds. Unlike Time.realtimeSinceStartup, this is not reset when starting play mode.

See Also: Time.realtimeSinceStartup

Simple Editor Window that saves each 300 seconds the current scene.

// Simple editor window that autosaves the working scene
// Make sure to have this window opened to be able to execute the auto save.

import UnityEditor;

class SimpleAutoSave extends EditorWindow {
    
    var saveTime : float = 300;
    var nextSave : float = 0;

    @MenuItem("Example/Simple autoSave")
    static function Init() {
        var window : SimpleAutoSave = 
            EditorWindow.GetWindowWithRect(
                SimpleAutoSave, 
                Rect(0,0,165,40));
        window.Show();
    }
    function OnGUI() {
         EditorGUILayout.LabelField("Save Each:", saveTime + " Secs");
         var timeToSave : int = nextSave - EditorApplication.timeSinceStartup;
         EditorGUILayout.LabelField("Next Save:", timeToSave.ToString() + " Sec");
         this.Repaint();
         
        if(EditorApplication.timeSinceStartup > nextSave) {
            var path : String [] = EditorApplication.currentScene.Split(char.Parse("/"));
            path[path.Length -1] = "AutoSave_" + path[path.Length-1];    
            EditorApplication.SaveScene(String.Join("/",path));
            Debug.Log("Saved Scene");
            nextSave = EditorApplication.timeSinceStartup + saveTime;
        }
    }
}