Microsoft Office 2000/Visual Basic Programmer's Guide

Viewing the List of Available COM Add-ins

By default, there's no menu item or toolbar button to display the COM Add-ins dialog box, but you can easily display it.

To add a menu item or toolbar button for the COM Add-ins dialog box

1. In the Office 2000 application, click Customize on the Tools menu.
   
   
2. Click the Commands tab.
   
   
3. In the Categories list, click Tools.
   
   
4. In the Commands list, click COM Add-ins. You may have to scroll through the list to find it.
   
   
5. Drag the COM Add-ins command to a toolbar or a menu.
   
   
6. Close the Customize dialog box.

Note   In Microsoft Outlook 2000, you can also access the COM Add-ins dialog box by clicking Options on the Tools menu, clicking the Other tab, and then clicking Advanced Options. In the Advanced Options dialog box, click COM Add-ins.

When you click the COM Add-ins toolbar button or menu item, the COM Add-ins dialog box appears, showing the list of available COM add-ins. You can load (connect) or unload (disconnect) an add-in by selecting the check box next to it. Loading a COM add-in loads it into memory so that you can work with it. Unloading an add-in removes it from memory; you can't use the add-in until you load it again.

You can add a new COM add-in to the list by clicking Add and locating the add-in. Clicking Add and selecting an add-in that doesn't appear in the list registers the add-in DLL if it's not already registered, and adds the add-in to the list of available COM add-ins for an Office application. If you've copied the Image Gallery sample add-in to your computer, you can locate ImageGallery.dll and add it to the list of available COM add-ins in Word, Excel, or PowerPoint.

To remove a COM add-in from the list, select it and click Remove. Removing an add-in deletes the registry key that contains the add-in's name and load behavior. The registry contains information about a COM add-in in two places. Like any other DLL, the add-in's DLL is registered as a unique object on the system. Additionally, information about the add-in is placed in another section of the registry in order to notify Office applications that the add-in exists, and it's this section that's deleted when you remove an add-in from the list. The DLL itself remains registered, and if you add the add-in to the list again, the add-in's informational section is re-created in the registry.

Notes

• You can add only DLLs that are COM add-ins to the list of available add-ins in the COM Add-ins dialog box. Moreover, you can add only COM add-ins that are registered for the application you're working in. For example, if you're working in Access, you can't add a COM add-in that's registered only for Word and Excel.
  
  
• You can also create COM add-ins for the Visual Basic Editor. Loading and unloading a COM add-in for the Visual Basic Editor is slightly different than doing so for COM add-ins in the host application's user interface. For more information about working with COM add-ins for the Visual Basic Editor, see "Building COM Add-ins for the Visual Basic Editor" later in this chapter.