Question Flex not growing vertically in EditorWindows

This depends on how you're instantiating the UXML on your EditorWindow code basically! So the solution you used works, but you can also adjust it on the code side.

 

I meant that there's one call you can make to instantiate the UXML asset with a VisualElement parameter, and if you use that passing the root visual element from the window as that parameter, you'll get the full UXML copied into it and since it already takes the full window area, you won't need to set flex-grow to anything else.

Code (CSharp):

1. public class TestWindow : EditorWindow
2. {
3.     [SerializeField]
4.     private VisualTreeAsset m_VisualTreeAsset = default;
5.  
6.     [MenuItem("Window/UI Toolkit/TestWindow")]
7.     public static void ShowExample()
8.     {
9.         TestWindow wnd = GetWindow<TestWindow>();
10.         wnd.titleContent = new GUIContent("TestWindow");
11.     }
12.  
13.     public void CreateGUI()
14.     {
15.         // Each editor window contains a root VisualElement object
16.         m_VisualTreeAsset.CloneTree(rootVisualElement);
17.     }
18. }

Alternatively, you can create your own VisualElement (or TemplateContainer, which is a subclass of VisualElement) that has flex-grow set to 1 and clone into that variable, or directly set flex-grow to 1 in the TemplateContainer resulting from the call to Instantiate(), either by adding a USS class or setting it in code. Keep in mind that inlining styles is not ideal and USS classes are preferred, but it's possible to do so with code.

Code (CSharp):

1.  
2.     public void CreateGUI()
3.     {
4.         // Each editor window contains a root VisualElement object
5.         var clone = m_VisualTreeAsset.Instantiate();
6.      
7.         // Choice 1: set it in code.
8.         clone.style.flexGrow = 1;
9.      
10.         // Choice 2: enable a class on it that has flex-grow set to 1.
11.         clone.EnableInClassList("someClassNameWithFlexGrow", true);
12.      
13.         rootVisualElement.Add(clone);
14.     }