Outlook VSTO Handling SelectionChange correctly (currently doubleclick crashes Addin)

user_668338 0
Viewed 240

From what I understand you need to track Activation and Deactivation of the Explorers. During activation, you need to add SelectionChange event handlers for the current explorer. This seems to work perfectly for single clicks on AppointmentItems. But it crashes the Addin when double-clicking on an appointment series and selecting a single Appointment.

Here is the source: On class level 

    private Outlook.Explorer currentExplorer = null;
    private Outlook.AppointmentItem currentAppointmentItem = null;

within Startup:

       currentExplorer = this.Application.ActiveExplorer();

        ((Outlook.ExplorerEvents_10_Event)currentExplorer).Activate +=
        new Outlook.ExplorerEvents_10_ActivateEventHandler(
        Explorer_Activate);

        currentExplorer.Deactivate += new
        Outlook.ExplorerEvents_10_DeactivateEventHandler(
        Explorer_Deactivate);

The event handlers:

    void Explorer_Activate()
    {
        currentExplorer.SelectionChange += new Outlook.ExplorerEvents_10_SelectionChangeEventHandler(Selection_Change);
    }

    void Explorer_Deactivate()
    {
        currentExplorer.SelectionChange -= new Outlook.ExplorerEvents_10_SelectionChangeEventHandler(Selection_Change); ;
    }

    private void Close_Explorer()
    {

    }

    private void Selection_Change()
    {
        Outlook.MAPIFolder selectedFolder = currentExplorer.CurrentFolder;            
        if (currentExplorer.Selection.Count > 0)
        {
            Object selObject = currentExplorer.Selection[1];
            if (selObject is Outlook.AppointmentItem)
            {
                currentAppointmentItem = (Outlook.AppointmentItem)selObject;
            }
            else
            {
                currentAppointmentItem = null;
            }
        }
    }

What am I overlooking? Is the form of deregistering a problem?

outlook-addin vsto outlook
3 Answers

Try to add try/catch blocks to the event handlers. The Outlook object model can give you unpredictable results sometimes. It is worth adding them and find where an exception is thrown.

currentExplorer.Selection.Count

Also, you may subscribe to the SelectionChange event in the NewExplorer event and don't switch between explorers when they are activated or deactivated. The event is fired whenever a new explorer window is opened, either as a result of user action or through program code.

user_16033510

The only thing which I added was a handler for NewInspector and InspectorClose events along with Marshal.ReleaseComObject(). The only thing which I can imagine that double clicking while debugging I got in some kind of race condition (because double clicking also triggers the Selection_Change event). But this is only a guess.

user_6683380

You do not need to add and remove event handlers as an explorer is activated / deactivated. Are you trying to support multiple explorers? In that case, create a wrapper class that hold the Explorer object as it member and uses its methods as event handlers.

user_3320590
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