Question

I have RichTextBox in WPF which contains InlineUIContainer with some custom objects. How to allow Undo event for that UIContainer?

Answer 1

First of all bind a command to your undo button.
Write a CommandBinding similar to this:
<CommandBinding Command="Undo" Executed="ExecuteUndo" CanExecute="CanExecuteUndo"/>

Then set the Content of the RichTextBox to something like this

{Binding myUndoManager.CurrentContent, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}

myUndoManager is a DependencyProperty with type of UndoManager class. You need to implement this class and inherit it from DependencyObject and INotifyPropertyChanged. within this class, CurrentContent is a DependencyProperty which keeps the proper content to show and PropertyChanged event handles every changes to the Content of the RichTextBox. (you can add a collection to the class and with each call to this event, add a new item to the collection. the type of the items for this collection might have some properties like TextDifferences, ActionType, …)

Then all that is left is to implement the body of CanExecuteUndo and ExecuteUndo inside your code. (e.CanExecute could be set to true inside the CanExecuteUndo, if and only if the collection is not empty. And ExecuteUndo pops out the last item from the collection and according to its ActionType does the necessary actions)

And don’t forget to set the DataContext of the window(or RichTextBox) to {Binding RelativeSource={RelativeSource Self}} if myUndoManager object is in the same class as the window.