How to force Unity to Repaint an EditorWindow?

Hi, I have a problem with the OnGUI method:

In an EditorWindow class, I have

 void OnGUI()
 {
     _loadingDots += "."; 
 
     if(_loadingDots.Length >= 4)
         _loadingDots = ".";
         
     GUILayout.Label("Importing" + _loadingDots, EditorStyles.boldLabel);
     Repaint();
 }

And in the Update:

void Update()

{

     _timer += Time.deltaTime;
 
     if(!_isProcessBusy)
     {
         if(_timer >= 0.5f)
             _isProcessFree = true;
     }
 
     if(_isProcessFree)
     {
         _isProcessFree = false;
         _isProcessBusy = true;
         Import();
     }
 }

The problem is that when the Import() method is called the GUI freezes, but when the Import method finish then it repaints, How could I force to repaint? I know I'm using the Repaint method, but it seems doesn't work or the OnGUI or Update are not called until the Import method finish.