Fix crush on popup close during selection

[jl0pd]

Our application have several popups, one of which is shown when mouse is over member. Lifetime of all popups in controlled manually and CompletionWindowBase.Hide() is called when selection is changed. Hiding popup results in following exception:

AvaloniaEdit.Rendering.VisualLinesInvalidException: Exception of type 'AvaloniaEdit.Rendering.VisualLinesInvalidException' was thrown.
   at AvaloniaEdit.Rendering.TextView.get_VisualLines()
   at AvaloniaEdit.Rendering.BackgroundGeometryBuilder.GetRectsForSegmentImpl(TextView textView, ISegment segment, Boolean extendToFullWidthAtLineEnd)+MoveNext()
   at AvaloniaEdit.Rendering.BackgroundGeometryBuilder.AddSegment(TextView textView, ISegment segment)
   at AvaloniaEdit.Editing.SelectionLayer.Render(DrawingContext drawingContext)
   at Avalonia.Rendering.Composition.CompositingRenderer.UpdateCore()
   at Avalonia.Rendering.Composition.CompositingRenderer.Update()
   at Avalonia.Rendering.Composition.Compositor.CommitCore()
   at Avalonia.Rendering.Composition.Compositor.Commit()
   at Avalonia.Media.MediaContext.CommitCompositor(Compositor compositor)
   at Avalonia.Media.MediaContext.SyncCommit(Compositor compositor, Boolean waitFullRender, Boolean catchExceptions)
   at Avalonia.Media.MediaContext.SyncDisposeCompositionTarget(CompositionTarget compositionTarget)
   at Avalonia.Rendering.Composition.CompositingRenderer.Dispose()
   at Avalonia.Controls.TopLevel.HandleClosed()
   at Avalonia.Controls.WindowBase.HandleClosed()
   at Avalonia.Win32.WindowImpl.AppWndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
   at Avalonia.Win32.PopupImpl.WndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
   at Avalonia.Win32.WindowImpl.WndProcMessageHandler(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
   at Avalonia.Win32.Interop.UnmanagedMethods.DestroyWindow(IntPtr hwnd)
   at Avalonia.Win32.Interop.UnmanagedMethods.DestroyWindow(IntPtr hwnd)
   at Avalonia.Win32.WindowImpl.Dispose()
   at Avalonia.Controls.Primitives.PopupRoot.Dispose()
   at Avalonia.Controls.Primitives.Popup.<>c.<Open>b__101_8(ValueTuple`2 state)
   at Avalonia.Reactive.Disposable.AnonymousDisposable`1.Dispose()
   at Avalonia.Controls.Primitives.Popup.PopupOpenState.Dispose()
   at Avalonia.Controls.Primitives.Popup.CloseCore()
   at Avalonia.Controls.Primitives.Popup.Close()
   at OurApp.EditorView.CloseAllWindows()
   at OurApp.EditorView.<.ctor>b__7_0(Object _, EventArgs _)
   at AvaloniaEdit.Editing.TextArea.set_Selection(Selection value)
   at AvaloniaEdit.Editing.SelectionMouseHandler.ExtendSelectionToMouse(PointerEventArgs e)
   at AvaloniaEdit.Editing.SelectionMouseHandler.TextArea_MouseMove(Object sender, PointerEventArgs e)
   at Avalonia.Interactivity.EventRoute.RaiseEventImpl(RoutedEventArgs e)
   at Avalonia.Interactivity.Interactive.RaiseEvent(RoutedEventArgs e)
   at Avalonia.Input.MouseDevice.ProcessRawEvent(RawPointerEventArgs e)
   at Avalonia.Threading.Dispatcher.Send(SendOrPostCallback action, Object arg, Nullable`1 priority)
   at Avalonia.Controls.TopLevel.HandleInput(RawInputEventArgs e)
   at Avalonia.Win32.WindowImpl.AppWndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
   at Avalonia.Win32.WindowImpl.WndProcMessageHandler(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
   at Avalonia.Win32.Interop.UnmanagedMethods.DispatchMessage(MSG& lpmsg)
   at Avalonia.Win32.Interop.UnmanagedMethods.DispatchMessage(MSG& lpmsg)
   at Avalonia.Win32.Win32DispatcherImpl.RunLoop(CancellationToken cancellationToken)
   at Avalonia.Threading.DispatcherFrame.Run(IControlledDispatcherImpl impl)
   at Avalonia.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at Avalonia.Threading.Dispatcher.MainLoop(CancellationToken cancellationToken)
   at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.StartCore(String[] args)
   at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(String[] args)
   at Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime(AppBuilder builder, String[] args, Action`1 lifetimeBuilder)
   at OurApp.Program.Main(String[] args)

I was unable to reproduce same error on sample project

[maxkatz6]

This issue was fixed on Avalonia side
AvaloniaUI/Avalonia#17784
AvaloniaUI/Avalonia#18119

Root of the problem was extra render call during window disposal.

[grokys]

@maxkatz6 would it still make sense to have this PR merged to support earlier Avalonia versions?

Approved too soon