I solved the issue....removed specific mouse events and reorded a few lines in LayoutDocumentTabItem

protected override void OnMouseDown(System.Windows.Input.MouseButtonEventArgs e)
{
if (e.ChangedButton == MouseButton.Middle)
{
if (LayoutItem.CloseCommand.CanExecute(null))
LayoutItem.CloseCommand.Execute(null);
}
if (e.ChangedButton == MouseButton.Left)
{
var layoutDocument = Model as LayoutDocument;
if ((layoutDocument != null) && !layoutDocument.CanMove)
return;

			if (e.ClickCount == 1)
			{
				_mouseDownPoint = e.GetPosition(this);
				_isMouseDown = true;
			}
			e.Handled = true;
		}
		base.OnMouseDown(e);
	}

	protected override void OnMouseMove(System.Windows.Input.MouseEventArgs e)
	{
		base.OnMouseMove(e);

		if (_isMouseDown)
		{
			Point ptMouseMove = e.GetPosition(this);

			if (Math.Abs(ptMouseMove.X - _mouseDownPoint.X) > SystemParameters.MinimumHorizontalDragDistance ||
				Math.Abs(ptMouseMove.Y - _mouseDownPoint.Y) > SystemParameters.MinimumVerticalDragDistance)
			{
				this.UpdateDragDetails();
				this.CaptureMouse();
				_isMouseDown = false;
			}
		}

		if (this.IsMouseCaptured)
		{
			var mousePosInScreenCoord = this.PointToScreenDPI(e.GetPosition(this));
			if (!_parentDocumentTabPanelScreenArea.Contains(mousePosInScreenCoord))
			{
				this.StartDraggingFloatingWindowForContent();
			}
			else
			{
				int indexOfTabItemWithMouseOver = _otherTabsScreenArea.FindIndex(r => r.Contains(mousePosInScreenCoord));
				if (indexOfTabItemWithMouseOver >= 0)
				{
					var targetModel = _otherTabs[indexOfTabItemWithMouseOver].Content as LayoutContent;
					var container = this.Model.Parent as ILayoutContainer;
					var containerPane = this.Model.Parent as ILayoutPane;

					if ((containerPane is LayoutDocumentPane) && !((LayoutDocumentPane)containerPane).CanRepositionItems)
						return;
					if ((containerPane.Parent != null) && (containerPane.Parent is LayoutDocumentPaneGroup) && !((LayoutDocumentPaneGroup)containerPane.Parent).CanRepositionItems)
						return;

					var childrenList = container.Children.ToList();
					containerPane.MoveChild(childrenList.IndexOf(Model), childrenList.IndexOf(targetModel));
					this.Model.IsActive = true;
					_parentDocumentTabPanel.UpdateLayout();
					this.UpdateDragDetails();
				}
			}
		}
	}

	protected override void OnMouseUp(MouseButtonEventArgs e)
	{
		base.OnMouseUp(e);

		if (IsMouseCaptured)
			ReleaseMouseCapture();

		_isMouseDown = false;
		Model.IsActive = true;

		e.Handled = true;
	}

	//protected override void OnMouseLeftButtonUp(System.Windows.Input.MouseButtonEventArgs e)
	//{
	//	if (IsMouseCaptured)
	//		ReleaseMouseCapture();
	//	_isMouseDown = false;

	//	base.OnMouseLeftButtonUp(e);
	//	e.Handled = true;
	//}

	protected override void OnMouseLeave(System.Windows.Input.MouseEventArgs e)
	{
		base.OnMouseLeave(e);
		_isMouseDown = false;
	}

	protected override void OnMouseEnter(MouseEventArgs e)
	{
		base.OnMouseEnter(e);
		_isMouseDown = false;
	}

	//protected override void OnMouseDown(MouseButtonEventArgs e)
	//{
	//	if (e.ChangedButton == MouseButton.Middle)
	//	{
	//		if (LayoutItem.CloseCommand.CanExecute(null))
	//			LayoutItem.CloseCommand.Execute(null);
	//	}

	//	base.OnMouseDown(e);
	//}

Hi,
Is this issue still present in the latest v3.8 version available for free for 45 days here : https://xceed.com/xceed-toolkit-plus-for-wpf/ ?

Hi,
yes, stil present (the code is the same in LayoutDocumentTabItem). - I tried the download.
btw, i am quite sure was not there in free 3.0
bye

Hi,
Can you submit a sample project running in XBAP mode so we can test the same scenario as the one you are getting ? Does it happens all the time or just some times ?
Thank you.

Hi,
no, I can't provide source because too big with services, db ...
not allways but quite often
we are using a user control hosted in WPF or XBAP container, code below but quite sure a simple doc collection is enough ??

<Grid >
	<Grid.RowDefinitions>
		<RowDefinition Height="*"></RowDefinition>
		<RowDefinition Height="Auto"></RowDefinition>
	</Grid.RowDefinitions>

	<!--DOCKING-->

	<avalonDock:DockingManager x:Name="dockManager" Grid.Row="0" Background="Transparent"
			AnchorablesSource="{Binding Tools}"  
			DocumentsSource="{Binding Documents}"
			IsEnabled="{Binding Path=IsEnabled, ElementName=FooterView, Mode=OneWay}"
			ActiveContent="{Binding ActiveDocument, Mode=TwoWay, Converter={x:Static Converters:ActiveDocumentConverter.Instance}}"
			Behaviors:LayoutSerializerBehavior.LoadLayoutCommand="{Binding ADLayout.LoadLayoutCommand}"
			Behaviors:LayoutSerializerBehavior.SaveLayoutCommand="{Binding ADLayout.SaveLayoutCommand}">

		<avalonDock:DockingManager.Theme>
            <Themes:AvalonMetroTheme />
		</avalonDock:DockingManager.Theme>

        <avalonDock:DockingManager.DocumentHeaderTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal" x:Name="toto" Background="Transparent">
                    <TextBlock Text="{Binding Title}" TextTrimming="CharacterEllipsis"/>
                </StackPanel>
            </DataTemplate>
        </avalonDock:DockingManager.DocumentHeaderTemplate>

        <avalonDock:DockingManager.LayoutItemContainerStyleSelector>
			<Selectors:PanesStyleSelector>
				<Selectors:PanesStyleSelector.ToolStyle>
					<Style TargetType="{x:Type avalonDock:LayoutAnchorableItem}">
						<Setter Property="CanClose" Value="false"/>
						<Setter Property="CanFloat" Value="false"/>
                        <Setter Property="CanHide" Value="false"/>
                        <Setter Property="CloseCommand" Value="{Binding Model.CloseCommand}"/>
						<Setter Property="Title" Value="{Binding Model.DisplayName}"/>
						<Setter Property="ContentId" Value="{Binding Model.ContentId}"/>
						<Setter Property="IsSelected" Value="{Binding Model.IsSelected, Mode=TwoWay}"/>
						<Setter Property="IsActive" Value="{Binding Model.IsActive, Mode=TwoWay}"/>
					</Style>
				</Selectors:PanesStyleSelector.ToolStyle>
				<Selectors:PanesStyleSelector.DocumentStyle>
					<Style TargetType="{x:Type avalonDock:LayoutItem}">
						<Setter Property="CloseCommand" Value="{Binding Model.CloseCommand}"/>
						<Setter Property="Title" Value="{Binding Model.DisplayName}"/>
						<Setter Property="ToolTip" Value="{Binding Model.DisplayName}"/>
						<Setter Property="ContentId" Value="{Binding Model.ContentId}"/>
						<Setter Property="IsSelected" Value="{Binding Model.IsSelected, Mode=TwoWay}"/>
                        <Setter Property="IsActive" Value="{Binding Model.IsActive, Mode=TwoWay}"/>
                    </Style>
				</Selectors:PanesStyleSelector.DocumentStyle>
			</Selectors:PanesStyleSelector>
		</avalonDock:DockingManager.LayoutItemContainerStyleSelector>

		<avalonDock:LayoutRoot>
			<avalonDock:LayoutPanel Orientation="Vertical">
                
                <avalonDock:LayoutDocumentPaneGroup>
                    <avalonDock:LayoutDocumentPane/>
				</avalonDock:LayoutDocumentPaneGroup>
                
				<avalonDock:LayoutAnchorablePaneGroup DockHeight="250">
					<avalonDock:LayoutAnchorablePane Name="ToolsPane" DockHeight="250" />
				</avalonDock:LayoutAnchorablePaneGroup>
				
			</avalonDock:LayoutPanel>
		</avalonDock:LayoutRoot>
	</avalonDock:DockingManager>

	<!--FOOTER-->
	<Views:FooterView x:Name="FooterView" Grid.Row="1" />

</Grid>