The StartUpdateElement/EndUpdateElement methods record and add changes of the current element to the control's Undo/Redo queue. You can use the StartBlockUndoRedo / EndBlockUndoRedo methods to group multiple Undo/Redo operations into a single-block. The AllowUndoRedo property specifies whether the control supports undo/redo operations for objects (elements, links, ...). No entry is added to the Undo/Redo queue if no property is changed for the current element. Each call of the StartUpdateElement must be succeeded by a EndUpdateElement call. The UndoListAction property lists the Undo actions that can be performed in the chart. The RedoListAction property lists the Redo actions that can be performed in the chart.

The StartUpdateElement/EndUpdateElement methods can record changes for the following properties only:

• Caption, gets or sets a value that indicates the HTML caption to be displayed on the element
• Parent, defines the element's parent (when the element is part of a hierarchy)
• ChildPosition, specifies the position of the element while it is a child element (when the element is part of a hierarchy)
• ID, defines the element's unique identifier
• AutoSize, specifies if the element computes its size automatically
• X, specifies the element's x-position
• Y, specifies the element's y-position
• Width, specifies the width of the element
• Height, specifies the height of the element
• Visible, shows or hides the element
• Enabled, enables or disables the element
• BackColor, gets or sets a value that indicates the element's background color
• ForeColor, gets or sets a value that indicates the element's foreground color
• OverviewColor, gets or sets a value that indicates the element's overview color
• BorderColor, gets or sets a value that indicates the element's border color
• StatusColor, gets or sets a value that indicates the element's status color
• Pictures, specifies the list of pictures to be displayed on the element
• ExtraPictures, specifies the list of additional pictures to be displayed on the element
• ExtraCaption, gets or sets a value that indicates additional HTML caption to be displayed on the element
• Pattern, specifies the pattern to be shown on the element's background
• UserData, associates any extra data associated with the element

The Undo/Redo records show as:

• "UpdateElement;ELEMENTID", indicates that one or more properties of the element has been updated, using the StartUpdateElement / EndUpdateElement methods

within the UndoListAction/RedoListAction result