Disable ToolBar

Requirement 1:
I have developed an Excel Add-in.Whenever I install the addin in the excel workbook a toolbar is opened.
The code to open the toolBar is written in WorkBook_Open() method of workbook.
Now I close the workbook I want to disable my toolbar as there are not active sheet available in the workbook.
I have written the code to disable the toolbar in WorkBook_BeforeClose() method of workbook.But this is not working as when I close the workbook WorkBook_BeforeClose() event is not getting fired.This gets fired only when I close the Add-in Installed or when I Un-install the Add-in.

Code Snippet:
Private Sub Workbook_Open()

     On Error GoTo HandleErr
   
     g_sMarketAxessAddinFilename = Me.Path
     g_sMarketAxessAddinFilenameSansSuffix = getFileNameSansSuffix(Me.Path)
         
     'This piece of code sets the project path and creates Market Axess menu.
     Call setProjectPaths
     createMarketAxessMenu
     buildMAToolBar
     'Setting the category in insert function menu.
     Application.ScreenUpdating = False
     ThisWorkbook.IsAddin = False
     'This function sets the MarketAxess Category.
     Call addCategoryDescription
     ThisWorkbook.IsAddin = True
     Application.ScreenUpdating = True
     'finally, trick the add-in into thinking that it has been File / Save'd
     ThisWorkbook.Saved = True
     Exit Sub

HandleErr:
    Call handleError(MAWRKBOOKOPEN_ERR_NUM, Err, Now)
End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)
    Set MValidationChecks.oXmlDocValidationFile = Nothing
    Set ReadResponse.oXmlDocPropertyFile = Nothing
    disableMAToolbar
End Sub


Requirement 2:

I have added a custom category say "abc" in the excel which has many user defined function.
When I open any function in the custom category through Insert -> Function wizard, I want to show the description of the function,description of all the parameters of the function,data type of each parameter on the right side of the wizard.
Also I want to show mandatory parametes to appear in BOLD font and optional parameters to appear in PLAIN font.
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