Fix search pane and analyzer window

ILSpy.Avalonia.Core/Analyzers/AnalyzerTreeView.cs

@@ -73,7 +73,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 
 		public void Show()
 		{
-			if (!IsVisible)
+			if (VisualRoot == null)
 				MainWindow.Instance.ShowInBottomPane("Analyzer", this);
 		}
 

ILSpy.Avalonia.Core/Search/SearchPane.xaml.cs

@@ -97,7 +97,7 @@ namespace ICSharpCode.ILSpy.Search
 		
 		void MainWindow_Instance_CurrentAssemblyListChanged(object sender, NotifyCollectionChangedEventArgs e)
 		{
-			if (IsVisible) {
+			if (VisualRoot != null) {
 				StartSearch(this.SearchTerm);
 			} else {
 				StartSearch(null);
@@ -107,7 +107,7 @@ namespace ICSharpCode.ILSpy.Search
 		
 		public void Show()
 		{
-			if (!IsVisible) {
+			if (VisualRoot == null) {
 				MainWindow.Instance.ShowInTopPane("Search", this);
 				if (runSearchOnNextShow) {
 					runSearchOnNextShow = false;