Hm, I think I asked the wrong question. Under the "Browser extensions" I mean also the objects such as BHOs and custom ToolBands. The one way I know to add icon for this object is to create a key in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Extensions\<GUID> where GUID is a CLSID of my BHO or ToolBand object. In this key I specify the ButtonText and Icon values. After this manipulations I have: 1)Additional record in Manage Add-ons window 2)Icons for both records with specified CLSID. In this solution I don't like additional record in Manage Add-ons window. I will appreciate if someone will describe how to add icon for BHO or ToolBand without adding additional record in Manage Add-ons window.

Could you please describe how to add icon in IE8 Manage-Addons-Dialog for the Browser-Extension?

Only way I know is to check registry key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\Settings\<GUID>, where <GUID> is your toolbar CLSID. If value 'Flags' exists in this key, then your toolbar is disabled. If Flags value does not exists or whole key does not exists - your toolbar is enabled.