title: Need a LostFocus event for WinForms UserControl hosted in MS Office VBA through COM Interop
body: <p>We implemented an ActiveX control based on WinForms UserControl in VB.NET 2010. It is used on VBA UserForms through COM Interop. All works ok - except one thing. When the input focus is moved from the ActiveX to another VBA native control on the UserForm (like say Command Button), we cannot detect this thing. Such standard WinForms control events like Leave or Validating aren't triggered in this case.</p>
  
  <p>How to track it (better using a "managed" way, without WinAPI tricks)?</p>
  
  <p>Note that our UserControl contains other WinForms controls like buttons or textboxes, so we need a LostFocus event for the whole control exposed as an ActiveX regardless of what constituent part was selected.</p>