scrolling-a-wpf-treeview-or-grouped-listbox-in-a-virtualizingstackpanel-can-cause-a-hang.md

Scrolling a WPF TreeView or grouped ListBox in a VirtualizingStackPanel can cause an application to become unresponsive

Scope

Major

Version Introduced

4.5

Version Reverted

4.5.1

Source Analyzer Status

Planned

Change Description

In .NET Framework 4.5, scrolling a WPF xref:System.Windows.Controls.TreeView?displayProperty=name in a virtualized stack panel can cause an application to become unresponsive if there are margins in the viewport (between the items in the xref:System.Windows.Controls.TreeView?displayProperty=name, for example, or on an ItemsPresenter element). Additionally, in some cases, different sized items in the view can cause instability even if there are no margins.

• Quirked
• Build-time break

Recommended Action

This bug can be avoided by upgrading to .NET Framework 4.5.1. Alternatively, margins can be removed from view collections (like xref:System.Windows.Controls.TreeView?displayProperty=names) within virtualized stack panels if all contained items are the same size.

Affected APIs

• M:System.Windows.Controls.VirtualizingStackPanel.SetIsVirtualizing(System.Windows.DependencyObject,System.Boolean)

Category

Windows Presentation Foundation (WPF)

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