Question

I’ve added a combo box to my worksheet dynamically, and I want to delete the combo box dynamically at the end of two events – specifically the combobox.LostFocus and combobox.KeyDown events.

It currently works for two scenarios:

1. The use manually selects an item from the dropdown
2. The user partially types in an item and auto-completes fills in the rest, then the user hits enter on the keyboard.

It does NOT work if the user types in the entire text for a select, and presses enter. I get the message:

COMException was unhanded by user code: Unable to get the Name property of the OLEObject class

Visual Studio points to the line ‘sheetVSTO.Controls.Remove(myBox);’ in the myBox_LostFocus event handler as the source of the failure.

A user show be able to type the entire text into the combobox and press enter. Any help would be appreciated.

Here is what I have (let me know if more detailed needed):

    private void AddComboBox(String[] list)
    {
        Excel.Worksheet sheet = Globals.ThisAddIn.Application.ActiveSheet;
        Microsoft.Office.Tools.Excel.Worksheet sheetVSTO = Globals.Factory.GetVstoObject(sheet);
        Excel.Range cell = Globals.ThisAddIn.Application.ActiveCell;
        Microsoft.Office.Tools.Excel.Controls.ComboBox myBox= new Microsoft.Office.Tools.Excel.Controls.ComboBox();
        myBox.Name = "button1";
        myBox.Items.AddRange(list);
        myBox.KeyDown += new KeyEventHandler(myBox_KeyDown);
        myBox.LostFocus += new EventHandler(myBox_LostFocus);
        myBox.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
        myBox.AutoCompleteSource = AutoCompleteSource.ListItems;
        myBox.Focus();
        Microsoft.Office.Tools.Excel.ControlSite myBoxControl = sheetVSTO.Controls.AddControl(myBox, cell, boxName);
    }

    void myBox_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == System.Windows.Forms.Keys.Enter)
        {
            Microsoft.Office.Tools.Excel.Controls.ComboBox myBox = sender as Microsoft.Office.Tools.Excel.Controls.ComboBox;
            Excel.Worksheet sheet = Globals.ThisAddIn.Application.ActiveSheet;
            if (myBox.SelectedIndex > -1)
            {
                Microsoft.Office.Tools.Excel.Worksheet sheetVSTO = Globals.Factory.GetVstoObject(sheet);
                sheetVSTO.Controls.Remove(myBox);
            }
        }
    }
    void myBox_LostFocus(object sender, EventArgs e)
    {
        Microsoft.Office.Tools.Excel.Controls.ComboBox myBox = sender as Microsoft.Office.Tools.Excel.Controls.ComboBox;
        Excel.Worksheet sheet = Globals.ThisAddIn.Application.ActiveSheet;
        Microsoft.Office.Tools.Excel.Worksheet sheetVSTO = Globals.Factory.GetVstoObject(sheet);
        sheetVSTO.Controls.Remove(myBox);
    }

Answer 1

I found the answer!

I changed my 2 remove calls to this:

myBox.BeginInvoke(new MethodInvoker(delegate { sheetVSTO.Controls.Remove(myBox); }));