Add support for resizing header and footer

albyrock87 · albyrock87 · commit 025e9adedd49 · 2025-03-10T18:04:07.000+01:00
diff --git a/src/Controls/src/Core/Handlers/Items/iOS/ItemsViewController.cs b/src/Controls/src/Core/Handlers/Items/iOS/ItemsViewController.cs
@@ -199,7 +199,13 @@ public override void ViewWillAppear(bool animated)
 		public override void ViewWillLayoutSubviews()
 		{
 			ConstrainItemsToBounds();
-			InvalidateLayoutIfItemsMeasureChanged();
+
+			if (CollectionView is Items.MauiCollectionView { NeedsCellLayout: true } collectionView)
+			{
+				InvalidateLayoutIfItemsMeasureChanged();
+				collectionView.NeedsCellLayout = false;
+			}
+
 			base.ViewWillLayoutSubviews();
 			InvalidateMeasureIfContentSizeChanged();
 			LayoutEmptyView();
diff --git a/src/Controls/src/Core/Handlers/Items/iOS/MauiCollectionView.cs b/src/Controls/src/Core/Handlers/Items/iOS/MauiCollectionView.cs
@@ -10,6 +10,9 @@ internal class MauiCollectionView : UICollectionView, IUIViewLifeCycleEvents, IP
 	bool _invalidateParentWhenMovedToWindow;
 
 	WeakReference<ICustomMauiCollectionViewDelegate>? _customDelegate;
+
+	internal bool NeedsCellLayout { get; set; }
+
 	public MauiCollectionView(CGRect frame, UICollectionViewLayout layout) : base(frame, layout)
 	{
 	}
@@ -27,10 +30,12 @@ void IPlatformMeasureInvalidationController.InvalidateAncestorsMeasuresWhenMoved
 
 	void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating)
 	{
-		if (!isPropagating)
+		if (isPropagating)
 		{
-			SetNeedsLayout();
+			NeedsCellLayout = true;
 		}
+
+		SetNeedsLayout();
 	}
 
 	[UnconditionalSuppressMessage("Memory", "MEM0002", Justification = IUIViewLifeCycleEvents.UnconditionalSuppressMessage)]
diff --git a/src/Controls/src/Core/Handlers/Items/iOS/StructuredItemsViewController.cs b/src/Controls/src/Core/Handlers/Items/iOS/StructuredItemsViewController.cs
@@ -31,16 +31,6 @@ internal override void Disconnect()
 		{
 			base.Disconnect();
 
-			if (_headerViewFormsElement is not null)
-			{
-				_headerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;
-			}
-
-			if (_footerViewFormsElement is not null)
-			{
-				_footerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;
-			}
-
 			_headerUIView = null;
 			_headerViewFormsElement = null;
 			_footerUIView = null;
@@ -86,27 +76,23 @@ protected override CGRect DetermineEmptyViewFrame()
 
 		public override void ViewWillLayoutSubviews()
 		{
-			base.ViewWillLayoutSubviews();
-
-			// This update is only relevant if you have a footer view because it's used to place the footer view
-			// based on the ContentSize so we just update the positions if the ContentSize has changed
-			if (_footerUIView != null)
+			var hasHeaderOrFooter = _footerViewFormsElement is not null || _headerViewFormsElement is not null;
+			if (hasHeaderOrFooter && CollectionView is MauiCollectionView { NeedsCellLayout: true } collectionView)
 			{
-				var emptyView = CollectionView.ViewWithTag(EmptyTag);
-
-				if (IsHorizontal)
+				if (_headerViewFormsElement is not null)
 				{
-					if (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width ||
-						_footerUIView.Frame.X < emptyView?.Frame.X)
-						UpdateHeaderFooterPosition();
+					RemeasureLayout(_headerViewFormsElement);
 				}
-				else
+
+				if (_footerViewFormsElement is not null)
 				{
-					if (_footerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height ||
-						_footerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))
-						UpdateHeaderFooterPosition();
+					RemeasureLayout(_footerViewFormsElement);
 				}
+
+				UpdateHeaderFooterPosition();
 			}
+
+			base.ViewWillLayoutSubviews();
 		}
 
 		internal void UpdateFooterView()
@@ -123,15 +109,13 @@ internal void UpdateHeaderView()
 			UpdateHeaderFooterPosition();
 		}
 
-
 		internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag, ref UIView uiView, ref VisualElement formsElement)
 		{
 			uiView?.RemoveFromSuperview();
 
 			if (formsElement != null)
 			{
 				ItemsView.RemoveLogicalChild(formsElement);
-				formsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;
 			}
 
 			UpdateView(view, viewTemplate, ref uiView, ref formsElement);
@@ -150,7 +134,6 @@ internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag
 			if (formsElement != null)
 			{
 				RemeasureLayout(formsElement);
-				formsElement.MeasureInvalidated += OnFormsElementMeasureInvalidated;
 			}
 			else
 			{
@@ -176,7 +159,11 @@ void UpdateHeaderFooterPosition()
 				}
 
 				if (_footerUIView != null && (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width || emptyWidth > 0))
-					_footerUIView.Frame = new CoreGraphics.CGRect(ItemsViewLayout.CollectionViewContentSize.Width + emptyWidth, 0, footerWidth, CollectionView.Frame.Height);
+				{
+					_footerUIView.Frame = new CoreGraphics.CGRect(
+						ItemsViewLayout.CollectionViewContentSize.Width + emptyWidth, 0, footerWidth,
+						CollectionView.Frame.Height);
+				}
 
 				if (CollectionView.ContentInset.Left != headerWidth || CollectionView.ContentInset.Right != footerWidth)
 				{
@@ -249,14 +236,5 @@ protected override void HandleFormsElementMeasureInvalidated(VisualElement forms
 			var size = base.GetSize();
 			return new Size(size.Value.Width, size.Value.Height + (_headerUIView?.Frame.Height ?? 0) + (_footerUIView?.Frame.Height ?? 0));
 		}
-
-		internal void UpdateLayoutMeasurements()
-		{
-			if (_headerViewFormsElement != null)
-				HandleFormsElementMeasureInvalidated(_headerViewFormsElement);
-
-			if (_footerViewFormsElement != null)
-				HandleFormsElementMeasureInvalidated(_footerViewFormsElement);
-		}
 	}
 }
diff --git a/src/Controls/src/Core/Handlers/Items/iOS/TemplatedCell.cs b/src/Controls/src/Core/Handlers/Items/iOS/TemplatedCell.cs
@@ -288,7 +288,6 @@ void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating
 			if (!_measureInvalidated && _bound)
 			{
 				_measureInvalidated = true;
-				Superview?.SetNeedsLayout();
 			}
 		}
 
diff --git a/src/Controls/src/Core/Handlers/Items2/iOS/ItemsViewController2.cs b/src/Controls/src/Core/Handlers/Items2/iOS/ItemsViewController2.cs
@@ -189,15 +189,21 @@ public override void LoadView()
 
 		public override void ViewWillLayoutSubviews()
 		{
-			InvalidateLayoutIfItemsMeasureChanged();
+			if (CollectionView is Items.MauiCollectionView { NeedsCellLayout: true } collectionView)
+			{
+				InvalidateLayoutIfItemsMeasureChanged();
+				collectionView.NeedsCellLayout = false;
+			}
+
 			base.ViewWillLayoutSubviews();
 			LayoutEmptyView();
 			InvalidateMeasureIfContentSizeChanged();
 		}
 
 		void InvalidateLayoutIfItemsMeasureChanged()
 		{
-			var visibleCells = CollectionView.VisibleCells;
+			var collectionView = CollectionView;
+			var visibleCells = collectionView.VisibleCells;
 			List<NSIndexPath> invalidatedPaths = null;
 
 			var visibleCellsLength = visibleCells.Length;
@@ -206,7 +212,7 @@ void InvalidateLayoutIfItemsMeasureChanged()
 				if (visibleCells[n] is TemplatedCell2 { MeasureInvalidated: true } cell)
 				{
 					invalidatedPaths ??= new List<NSIndexPath>(visibleCellsLength);
-					var path = CollectionView.IndexPathForCell(cell);
+					var path = collectionView.IndexPathForCell(cell);
 					invalidatedPaths.Add(path);
 				}
 			}
@@ -215,7 +221,7 @@ void InvalidateLayoutIfItemsMeasureChanged()
 			{
 				var layoutInvalidationContext = new UICollectionViewLayoutInvalidationContext();
 				layoutInvalidationContext.InvalidateItems(invalidatedPaths.ToArray());
-				CollectionView.CollectionViewLayout.InvalidateLayout(layoutInvalidationContext);
+				collectionView.CollectionViewLayout.InvalidateLayout(layoutInvalidationContext);
 			}
 		}
 
diff --git a/src/Controls/src/Core/Handlers/Items2/iOS/StructuredItemsViewController2.cs b/src/Controls/src/Core/Handlers/Items2/iOS/StructuredItemsViewController2.cs
@@ -1,8 +1,8 @@
 #nullable disable
 using System;
+using System.Collections.Generic;
 using CoreGraphics;
 using Foundation;
-using Microsoft.Maui.Controls.Handlers.Items;
 using ObjCRuntime;
 using UIKit;
 
@@ -181,7 +181,52 @@ protected override CGRect DetermineEmptyViewFrame()
 
 		public override void ViewWillLayoutSubviews()
 		{
+			if (CollectionView is Items.MauiCollectionView { NeedsCellLayout: true })
+			{
+				InvalidateLayoutIfItemsMeasureChanged();
+			}
+
 			base.ViewWillLayoutSubviews();
 		}
+
+		void InvalidateLayoutIfItemsMeasureChanged()
+		{
+			var collectionView = CollectionView;
+			List<NSIndexPath> invalidatedPaths = null;
+			
+			if (ItemsView.Header is not null || ItemsView.HeaderTemplate is not null)
+			{
+				var visibleHeaders = collectionView.GetVisibleSupplementaryViews(UICollectionElementKindSectionKey.Header);
+				foreach (var header in visibleHeaders)
+				{
+					if (header is TemplatedCell2 { MeasureInvalidated: true } headerCell)
+					{
+						invalidatedPaths ??= new List<NSIndexPath>(2);
+						invalidatedPaths.Add(collectionView.IndexPathForCell(headerCell));
+					}
+				}
+			}
+
+
+			if (ItemsView.Footer is not null || ItemsView.FooterTemplate is not null)
+			{
+				var visibleFooters = collectionView.GetVisibleSupplementaryViews(UICollectionElementKindSectionKey.Footer);
+				foreach (var footer in visibleFooters)
+				{
+					if (footer is TemplatedCell2 { MeasureInvalidated: true } footerCell)
+					{
+						invalidatedPaths ??= new List<NSIndexPath>(1);
+						invalidatedPaths.Add(collectionView.IndexPathForCell(footerCell));
+					}
+				}
+			}
+
+			if (invalidatedPaths != null)
+			{
+				var layoutInvalidationContext = new UICollectionViewLayoutInvalidationContext();
+				layoutInvalidationContext.InvalidateItems(invalidatedPaths.ToArray());
+				collectionView.CollectionViewLayout.InvalidateLayout(layoutInvalidationContext);
+			}
+		}
 	}
 }
diff --git a/src/Controls/src/Core/Handlers/Items2/iOS/TemplatedCell2.cs b/src/Controls/src/Core/Handlers/Items2/iOS/TemplatedCell2.cs
@@ -283,7 +283,6 @@ void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating
 			if (!_measureInvalidated && _bound)
 			{
 				_measureInvalidated = true;
-				Superview?.SetNeedsLayout();
 			}
 		}
 	}
diff --git a/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25362.cs b/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25362.cs
@@ -13,8 +13,6 @@ public Issue25362(TestDevice device) : base(device)
 
 	[Test]
 	[Category(UITestCategories.CollectionView)]
-	[FailsOnIOSWhenRunningOnXamarinUITest("This is not working for CV2 yet")]
-	[FailsOnMacWhenRunningOnXamarinUITest("This is not working for CV2 yet")]
 	public void HeaderShouldNotCollapseWithItems()
 	{
 		App.WaitForElement("button");

Original file line number	Diff line number	Diff line change
`@@ -10,6 +10,9 @@ internal class MauiCollectionView : UICollectionView, IUIViewLifeCycleEvents, IP`
`10`	`10`	`bool _invalidateParentWhenMovedToWindow;`
`11`	`11`
`12`	`12`	`WeakReference<ICustomMauiCollectionViewDelegate>? _customDelegate;`
	`13`	`+`
	`14`	`+ internal bool NeedsCellLayout { get; set; }`
	`15`	`+`
`13`	`16`	`public MauiCollectionView(CGRect frame, UICollectionViewLayout layout) : base(frame, layout)`
`14`	`17`	`{`
`15`	`18`	`}`
`@@ -27,10 +30,12 @@ void IPlatformMeasureInvalidationController.InvalidateAncestorsMeasuresWhenMoved`
`27`	`30`
`28`	`31`	`void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating)`
`29`	`32`	`{`
`30`		`- if (!isPropagating)`
	`33`	`+ if (isPropagating)`
`31`	`34`	`{`
`32`		`- SetNeedsLayout();`
	`35`	`+ NeedsCellLayout = true;`
`33`	`36`	`}`
	`37`	`+`
	`38`	`+ SetNeedsLayout();`
`34`	`39`	`}`
`35`	`40`
`36`	`41`	`[UnconditionalSuppressMessage("Memory", "MEM0002", Justification = IUIViewLifeCycleEvents.UnconditionalSuppressMessage)]`
Original file line number	Diff line number	Diff line change
`@@ -31,16 +31,6 @@ internal override void Disconnect()`
`31`	`31`	`{`
`32`	`32`	`base.Disconnect();`
`33`	`33`
`34`		`- if (_headerViewFormsElement is not null)`
`35`		`- {`
`36`		`- _headerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;`
`37`		`- }`
`38`		`-`
`39`		`- if (_footerViewFormsElement is not null)`
`40`		`- {`
`41`		`- _footerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;`
`42`		`- }`
`43`		`-`
`44`	`34`	`_headerUIView = null;`
`45`	`35`	`_headerViewFormsElement = null;`
`46`	`36`	`_footerUIView = null;`
`@@ -86,27 +76,23 @@ protected override CGRect DetermineEmptyViewFrame()`
`86`	`76`
`87`	`77`	`public override void ViewWillLayoutSubviews()`
`88`	`78`	`{`
`89`		`- base.ViewWillLayoutSubviews();`
`90`		`-`
`91`		`- // This update is only relevant if you have a footer view because it's used to place the footer view`
`92`		`- // based on the ContentSize so we just update the positions if the ContentSize has changed`
`93`		`- if (_footerUIView != null)`
	`79`	`+ var hasHeaderOrFooter = _footerViewFormsElement is not null \|\| _headerViewFormsElement is not null;`
	`80`	`+ if (hasHeaderOrFooter && CollectionView is MauiCollectionView { NeedsCellLayout: true } collectionView)`
`94`	`81`	`{`
`95`		`- var emptyView = CollectionView.ViewWithTag(EmptyTag);`
`96`		`-`
`97`		`- if (IsHorizontal)`
	`82`	`+ if (_headerViewFormsElement is not null)`
`98`	`83`	`{`
`99`		`- if (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width \|\|`
`100`		`- _footerUIView.Frame.X < emptyView?.Frame.X)`
`101`		`- UpdateHeaderFooterPosition();`
	`84`	`+ RemeasureLayout(_headerViewFormsElement);`
`102`	`85`	`}`
`103`		`- else`
	`86`	`+`
	`87`	`+ if (_footerViewFormsElement is not null)`
`104`	`88`	`{`
`105`		`- if (_footerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height \|\|`
`106`		`- _footerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))`
`107`		`- UpdateHeaderFooterPosition();`
	`89`	`+ RemeasureLayout(_footerViewFormsElement);`
`108`	`90`	`}`
	`91`	`+`
	`92`	`+ UpdateHeaderFooterPosition();`
`109`	`93`	`}`
	`94`	`+`
	`95`	`+ base.ViewWillLayoutSubviews();`
`110`	`96`	`}`
`111`	`97`
`112`	`98`	`internal void UpdateFooterView()`
`@@ -123,15 +109,13 @@ internal void UpdateHeaderView()`
`123`	`109`	`UpdateHeaderFooterPosition();`
`124`	`110`	`}`
`125`	`111`
`126`		`-`
`127`	`112`	`internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag, ref UIView uiView, ref VisualElement formsElement)`
`128`	`113`	`{`
`129`	`114`	`uiView?.RemoveFromSuperview();`
`130`	`115`
`131`	`116`	`if (formsElement != null)`
`132`	`117`	`{`
`133`	`118`	`ItemsView.RemoveLogicalChild(formsElement);`
`134`		`- formsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;`
`135`	`119`	`}`
`136`	`120`
`137`	`121`	`UpdateView(view, viewTemplate, ref uiView, ref formsElement);`
`@@ -150,7 +134,6 @@ internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag`
`150`	`134`	`if (formsElement != null)`
`151`	`135`	`{`
`152`	`136`	`RemeasureLayout(formsElement);`
`153`		`- formsElement.MeasureInvalidated += OnFormsElementMeasureInvalidated;`
`154`	`137`	`}`
`155`	`138`	`else`
`156`	`139`	`{`
`@@ -176,7 +159,11 @@ void UpdateHeaderFooterPosition()`
`176`	`159`	`}`
`177`	`160`
`178`	`161`	`if (_footerUIView != null && (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width \|\| emptyWidth > 0))`
`179`		`- _footerUIView.Frame = new CoreGraphics.CGRect(ItemsViewLayout.CollectionViewContentSize.Width + emptyWidth, 0, footerWidth, CollectionView.Frame.Height);`
	`162`	`+ {`
	`163`	`+ _footerUIView.Frame = new CoreGraphics.CGRect(`
	`164`	`+ ItemsViewLayout.CollectionViewContentSize.Width + emptyWidth, 0, footerWidth,`
	`165`	`+ CollectionView.Frame.Height);`
	`166`	`+ }`
`180`	`167`
`181`	`168`	`if (CollectionView.ContentInset.Left != headerWidth \|\| CollectionView.ContentInset.Right != footerWidth)`
`182`	`169`	`{`
`@@ -249,14 +236,5 @@ protected override void HandleFormsElementMeasureInvalidated(VisualElement forms`
`249`	`236`	`var size = base.GetSize();`
`250`	`237`	`return new Size(size.Value.Width, size.Value.Height + (_headerUIView?.Frame.Height ?? 0) + (_footerUIView?.Frame.Height ?? 0));`
`251`	`238`	`}`
`252`		`-`
`253`		`- internal void UpdateLayoutMeasurements()`
`254`		`- {`
`255`		`- if (_headerViewFormsElement != null)`
`256`		`- HandleFormsElementMeasureInvalidated(_headerViewFormsElement);`
`257`		`-`
`258`		`- if (_footerViewFormsElement != null)`
`259`		`- HandleFormsElementMeasureInvalidated(_footerViewFormsElement);`
`260`		`- }`
`261`	`239`	`}`
`262`	`240`	`}`
Original file line number	Diff line number	Diff line change
`@@ -288,7 +288,6 @@ void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating`
`288`	`288`	`if (!_measureInvalidated && _bound)`
`289`	`289`	`{`
`290`	`290`	`_measureInvalidated = true;`
`291`		`- Superview?.SetNeedsLayout();`
`292`	`291`	`}`
`293`	`292`	`}`
`294`	`293`
Original file line number	Diff line number	Diff line change
`@@ -189,15 +189,21 @@ public override void LoadView()`
`189`	`189`
`190`	`190`	`public override void ViewWillLayoutSubviews()`
`191`	`191`	`{`
`192`		`- InvalidateLayoutIfItemsMeasureChanged();`
	`192`	`+ if (CollectionView is Items.MauiCollectionView { NeedsCellLayout: true } collectionView)`
	`193`	`+ {`
	`194`	`+ InvalidateLayoutIfItemsMeasureChanged();`
	`195`	`+ collectionView.NeedsCellLayout = false;`
	`196`	`+ }`
	`197`	`+`
`193`	`198`	`base.ViewWillLayoutSubviews();`
`194`	`199`	`LayoutEmptyView();`
`195`	`200`	`InvalidateMeasureIfContentSizeChanged();`
`196`	`201`	`}`
`197`	`202`
`198`	`203`	`void InvalidateLayoutIfItemsMeasureChanged()`
`199`	`204`	`{`
`200`		`- var visibleCells = CollectionView.VisibleCells;`
	`205`	`+ var collectionView = CollectionView;`
	`206`	`+ var visibleCells = collectionView.VisibleCells;`
`201`	`207`	`List<NSIndexPath> invalidatedPaths = null;`
`202`	`208`
`203`	`209`	`var visibleCellsLength = visibleCells.Length;`
`@@ -206,7 +212,7 @@ void InvalidateLayoutIfItemsMeasureChanged()`
`206`	`212`	`if (visibleCells[n] is TemplatedCell2 { MeasureInvalidated: true } cell)`
`207`	`213`	`{`
`208`	`214`	`invalidatedPaths ??= new List<NSIndexPath>(visibleCellsLength);`
`209`		`- var path = CollectionView.IndexPathForCell(cell);`
	`215`	`+ var path = collectionView.IndexPathForCell(cell);`
`210`	`216`	`invalidatedPaths.Add(path);`
`211`	`217`	`}`
`212`	`218`	`}`
`@@ -215,7 +221,7 @@ void InvalidateLayoutIfItemsMeasureChanged()`
`215`	`221`	`{`
`216`	`222`	`var layoutInvalidationContext = new UICollectionViewLayoutInvalidationContext();`
`217`	`223`	`layoutInvalidationContext.InvalidateItems(invalidatedPaths.ToArray());`
`218`		`- CollectionView.CollectionViewLayout.InvalidateLayout(layoutInvalidationContext);`
	`224`	`+ collectionView.CollectionViewLayout.InvalidateLayout(layoutInvalidationContext);`
`219`	`225`	`}`
`220`	`226`	`}`
`221`	`227`
Original file line number	Diff line number	Diff line change
`@@ -283,7 +283,6 @@ void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating`
`283`	`283`	`if (!_measureInvalidated && _bound)`
`284`	`284`	`{`
`285`	`285`	`_measureInvalidated = true;`
`286`		`- Superview?.SetNeedsLayout();`
`287`	`286`	`}`
`288`	`287`	`}`
`289`	`288`	`}`
Original file line number	Diff line number	Diff line change
`@@ -13,8 +13,6 @@ public Issue25362(TestDevice device) : base(device)`
`13`	`13`
`14`	`14`	`[Test]`
`15`	`15`	`[Category(UITestCategories.CollectionView)]`
`16`		`- [FailsOnIOSWhenRunningOnXamarinUITest("This is not working for CV2 yet")]`
`17`		`- [FailsOnMacWhenRunningOnXamarinUITest("This is not working for CV2 yet")]`
`18`	`16`	`public void HeaderShouldNotCollapseWithItems()`
`19`	`17`	`{`
`20`	`18`	`App.WaitForElement("button");`