Why I don't see any more the TextField inside OnGUI in EditorWindow script?

Question

using UnityEngine;
using UnityEditor;

public class SearchableWindow : EditorWindow
{
    string searchString = "";

    [MenuItem("Tools/Searching")]
    private static void Searching()
    {
        const int width = 340;
        const int height = 420;

        var x = (Screen.currentResolution.width - width) / 2;
        var y = (Screen.currentResolution.height - height) / 2;

        GetWindow<SearchableWindow>().position = new Rect(x, y, width, height);
    }


    void OnGUI()
    {
        GUILayout.BeginHorizontal(EditorStyles.toolbar);
        GUILayout.FlexibleSpace();
        searchString = GUILayout.TextField(searchString, EditorStyles.toolbarTextField);
        GUILayout.EndHorizontal();

        var items = Selection.gameObjects;
        // Do comparison here. For example
        for (int i = 0; i < items.Length; i++)
        {
            if (items[i].name.Contains(searchString))
            {
                GUILayout.Label(items[i].name);
            }
        }
    }
}

Before it was working fine but now everything is very slow and also I don't see the TextField and when selecting a GameObject in the Hierarchy it's taking almost 5 seconds to show it in the Editor Window.

And before it was all fast and showing the whole Hierarchy in the Editor Window.

Now it's empty:

I took the answer from this question:

Searchable

Answer 1

OnGUI is only called while the mouse is (moved/clicked) over the according Window -> it is not taking almost 5 seconds but until you move your mouse over the window again.

In order to solve that you could implement EditorWindow.OnSelectionChange and force a EditorWindow.Repaint so your window is refreshed everytime the Selection changes.

private void OnSelectionChange()
{
    Repaint();
}

---

The second issue is produced as follows:

GUILayout.TextField together with GUILayout.FlexibleSpace if not defined different uses automatically the width of the inserted text -> Since you have an empty text at start the width is almost 0 ... you actually can see your TextField very thin there and it gets bigger as you fill it:

Using the drawers from the EditorGUILayout instead solves this:

EditorGUILayout.BeginHorizontal(EditorStyles.toolbar);
GUILayout.FlexibleSpace();
searchString = EditorGUILayout.TextField(searchString, EditorStyles.toolbarTextField);
EditorGUILayout.EndHorizontal();

var items = Selection.gameObjects;
// Do comparison here. For example
foreach (var selectedObject in selected)
{
    if (selectedObject .name.Contains(searchString))
    {
        EditorGUILayout.LabelField(selectedObject.name);
    }
}

Tip If you replace

EditorGUILayout.LabelField(items[i].name);

with

if (GUILayout.Button(selectedObject.name, EditorStyles.label))
{
    EditorGUIUtility.PingObject(selectedObject);
}

you can click on the name and "ping" the according GameObject in the hierachy!

---

Update since asked in the comments

If you want to include all children of the selection recursive you could do something like (there might be better ways but that's what I came up with within 10 minutes)

private static IEnumerable<GameObject> GetChildrenRecursive(GameObject root)
{
    var output = new List<GameObject>();

    //add the root object itself
    output.Add(root);

    // iterate over direct children
    foreach (Transform child in root.transform)
    {
        // add the child itslef
        output.Add(child.gameObject);

        // Recursion here: Get all subchilds of this child
        var childsOfchild = GetChildrenRecursive(child.gameObject);
        output.AddRange(childsOfchild);
    }

    return output;
}

private static IEnumerable<GameObject> GetChildrenRecursive(IEnumerable<GameObject> rootObjects)
{
    var output = new List<GameObject>();


    foreach (var root in rootObjects)
    {
        output.AddRange(GetChildrenRecursive(root));
    }

    // remove duplicates
    return output.Distinct().ToList();
}

and using

var selected = GetChildrenRecursive(Selection.gameObjects);

Another Update

Since this might not be very efficient you probably should move it to Searching and than only refresh the selected value also in OnSelectionChange like

public class SearchableWindow : EditorWindow
{
    private string searchString = "";
    private List<GameObject> selected;

    [MenuItem("Tools/Searching")]
    private static void Searching()
    {
        const int width = 340;
        const int height = 420;

        var x = (Screen.currentResolution.width - width) / 2;
        var y = (Screen.currentResolution.height - height) / 2;

        var window = GetWindow<SearchableWindow>();
        window.position = new Rect(x, y, width, height);

        window.selected = GetChildrenRecursive(Selection.gameObjects).ToList();
    }

    private void OnSelectionChange()
    {
        selected = GetChildrenRecursive(Selection.gameObjects).ToList();
        Repaint();
    }

    private void OnGUI()
    {
        EditorGUILayout.BeginHorizontal(EditorStyles.toolbar);
        GUILayout.FlexibleSpace();
        searchString = EditorGUILayout.TextField(searchString, EditorStyles.toolbarTextField);
        EditorGUILayout.EndHorizontal();

        // only as fallback
        if (selected == null)
        {
            selected = GetChildrenRecursive(Selection.gameObjects).ToList();
        }

        // Do comparison here. For example
        foreach (var selectedObject in selected)
        {
            if (selectedObject.name.Contains(searchString))
            {
                if (GUILayout.Button(selectedObject.name, EditorStyles.label))
                {
                    EditorGUIUtility.PingObject(selectedObject);
                }
            }
        }
    }

    private static IEnumerable<GameObject> GetChildrenRecursive(GameObject root)
    {
        var output = new List<GameObject>();

        //add the root object itself
        output.Add(root);

        // iterate over direct children
        foreach (Transform child in root.transform)
        {
            // add the children themselves
            output.Add(child.gameObject);

            var childsOfchild = GetChildrenRecursive(child.gameObject);
            output.AddRange(childsOfchild);
        }



        return output;
    }

    private static IEnumerable<GameObject> GetChildrenRecursive(IEnumerable<GameObject> rootObjects)
    {
        var output = new List<GameObject>();

        foreach (var root in rootObjects)
        {
            output.AddRange(GetChildrenRecursive(root));
        }

        // remove any duplicates that would e.g. appear if you select a parent and its child
        return output.Distinct();
    }
}

---