SelectionChange for enter and backspace keys

Question

Hello all,
Our VSTO addin needs to know the current selection so we can sync our taskpane with current selection. We are using the SelectionChanged event to register our taskpane synch routine. The problem is that this event doesn't fire on Enter or backspace key.
We are specifically interested in the scenarios where the Enter/backspace results in a paragraph change(para add on enter and paragraph remove on backspace of the last character in a para). It seems like a bug to me that SelectionChange wont
fire on backspace when the delete key does fires it.
Is there any other workaround to detect this paragraph change state?

Answer 1

Hi,
>> I am not interested in a cursor change but rather a paragraph change which would indicate a change from one para to next.
The current object model does not have an event to be triggered when changing the content.
If you want to detect the paragraph changing, we could also use a global Timer to detect the paragraph changing of the active document.
>> Multiple documents - i would have to suspend/reactivate my timer on Activate/Deactivate events
>> Multiple windows of the same document - If i have the same document open in multiple windows, split window, new window etc, how would this timer work?
Here is the sample code for your reference:
using System.Collections.Generic;
using Word = Microsoft.Office.Interop.Word;
using System.Timers;
using System.Runtime.InteropServices;
namespace WordSelectionChangeIssue
public partial class ThisAddIn
private Timer addInTimer { get; set; }
private Dictionary<string, int> ParagraphCountDict { get; set; }
private void ThisAddIn_Startup(object sender, System.EventArgs e)
addInTimer = new System.Timers.Timer();
ParagraphCountDict = new Dictionary<string, int>();
addInTimer.Interval = 1000;
addInTimer.Elapsed += TimerElapsedHandler;
addInTimer.Start();
private void BindToChange(Word.Document document)
ParagraphCountDict.Add(document.Name, document.Paragraphs.Count);
private void TimerElapsedHandler(object sender, ElapsedEventArgs e)
if(Application.Documents.Count == 0)
return;
try
var activeDocument = Application.ActiveDocument;
if (!ParagraphCountDict.ContainsKey(activeDocument.Name))
BindToChange(activeDocument);
var previousParagraphsCount = ParagraphCountDict[activeDocument.Name];
var count = activeDocument.Paragraphs.Count;
if (previousParagraphsCount != count)
ParagraphCountDict[activeDocument.Name] = count;
// trigger event
ParagraphChangeHanlder(activeDocument);
}catch(COMException comEx)
private void ParagraphChangeHanlder(Word.Document document)
System.Windows.Forms.MessageBox.Show("Paragraph Changed!");
private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
addInTimer.Stop();
#region VSTO generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InternalStartup()
this.Startup += new System.EventHandler(ThisAddIn_Startup);
this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
#endregion
Regards,
Jeffrey
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