Resolved how to fix a position of an element to the bottom of a window?

I want to place a button in the lower right corner of the window, and its position relative to the lower right corner shall not change with the size of the window. For instance:



The "next" button at the lower right. However, no matter how I set its parameters, it seems not responsive at all.

I've tried to set the position to absolute, and set bottom and right to a fixed value, and adjusting the margin, but none of them worked. Can anyone help me?

 

Hi there, many thanks!

Actually I just figured out that the reason of my previous code's not working, which is because of the C# code behind.

When you create a new editor window using UI Builder, some snippets will be generated automatically. However, they are not really "proper". The code is like:

Code (CSharp):

1. public class DemoWindow : EditorWindow
2. {
3.     [MenuItem("Window/UI Toolkit/DemoWindow")]
4.     public static void ShowExample()
5.     {
6.         DemoWindow wnd = GetWindow<DemoWindow>();
7.         wnd.titleContent = new GUIContent("DemoWindow");
8.     }
9.  
10.     public void CreateGUI()
11.     {
12.         // Each editor window contains a root VisualElement object
13.         VisualElement root = rootVisualElement;
14.  
15.         // VisualElements objects can contain other VisualElement following a tree hierarchy.
16.         VisualElement label = new Label("Hello World! From C#");
17.         root.Add(label);
18.  
19.         // Import UXML
20.         var visualTree = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>("Assets/Scripts/CustomWindows/DemoWindow.uxml");
21.         VisualElement labelFromUXML = visualTree.Instantiate();
22.         root.Add(labelFromUXML);
23.     }
24. }

The thing is, the visual tree will be added to the root, or say, being a child of it, and then, there will be a root visual element whose size is auto. (This is just my personal understanding, it may not be right).

To fix this problem, instead of instantiate a new visual element and add it to the root, actually we can clone the visual tree to the root, and then there will be no more additional parent visual element.

Code (CSharp):

1. var visualTree = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>("Assets/Scripts/CustomWindows/DemoWindow.uxml");
2. visualTree.CloneTree(rootVisualElement);

I found the answer here: Making a listview fill space - Unity Forum