I assign keyboard shortcut to open a VBA UserForm in Excel. For some reason when UserForm is shown Excel activates the workbook which was active the first time the UserForm was shown. The code is vanilla. Does anyone know why it happens and how to fix it?

Sub AssignShortcuts()
    Application.OnKey "^+%s", "UserFormShow"
End Sub

Sub UserFormShow()
    UserForm.Show
End Sub

Sub CloseButton_Click()
    Me.Hide
End Sub

I tried capturing and reactivating active workbook in UserFormShow(), but it didn’t help. Debug.print outputs the right workbook, but it is not activated.

Sub UserFormShow()
    Dim wb As Workbook
    Set wb = ActiveWorkbook  
    frmMain.Show 
    wb.Activate
    Debug.Print "Activated Workbook: " & wb.Name
End Sub