The behavior makes sure the container Grid is set to Visibile only if the mass editing mode is not turned on (MassEditViewModel is null) and the context object has child document(s) (Documents.Items.Count is greater than 0. You can combine any number of binding results (MultiBindingItem) using the VisLogicAndConverter (the name should be self explanatory).
=== InvokeForAllItemsCommand InvokeOnItemsCommand {{Version/WinXSince|3.6}} ===
Available on all ListViewModels, this command allows executing a specified command on a collection of list items. It can be used in combination with features such as [[Mass_Edit_(UBIK_WinX)|mass editing]] and [[XAML_Changes_in_UBIK_WinX_3.5#After_3.5|expression based collection filtering]]. Examples for both combinations are provided below.
{{Attention|The command specified through the "Command" parameter is executed on list items and, therefore, must be available in the list item contexts (view models). If in doubt, the [[Developer_Mode|developer mode]] can be used to inspect if a command is available in a certain context.}}
{{Hint|Parameter "Command" and "SelectedItemsOnly" are specific to the InvokeForAllItemsCommandInvokeOnItemsCommand. What other parameters to define or whether to define them at all depends on the type of command to be executed on the items.}}
==== Invoke on selected items ====
<AppBarButton
xmlns:example="using:UBIK.WinX.Controls"
Command="{Binding Children.InvokeForAllItemsCommandInvokeOnItemsCommand}"
Icon="AllApps"
Label="Set to 50%"
<AppBarButton
xmlns:example="using:UBIK.WinX.Controls"
Command="{Binding Source={StaticResource Filtered}, Path=ListViewModel.InvokeForAllItemsCommandInvokeOnItemsCommand}"
Icon="AllApps"
Label="Set to 50"