Fix close and destroy of modal dialog

[sundaramramaswamy]

ISSUE
Moving the parent window after dismissal of modal pop-up leads to a crash in DefWindowProc.

FIX
AppWindow.Destroy not getting called and hence the parent window wasn’t receiving input events consumed by the popup. The right order of popup close/destroy is

0. [Optional] Island.Close
1. Bridge.Hide
2. AppWindow.Destroy
3. Bridge.Close

This is the reverse of the creation/show order.

CLEAN-UP

• Drop EnableWindow as it’s unneeded
  • This masked the underlying issue of not calling AppWindow.Destroy by forcing the parent to receive inputs without cleanly destroying the popup
  • This is automatically done by AppWindow.Destroy
• Call init_apartment first
  • Should be the very first call as it initializes COM internally
  • This should precede MddBootstrapInitialize2 call as noted
• Call SetForegroundWindow both on show and close modal
  • Former with popup as arg while latter with parent window
  • This is needed for proper focus on respective windows
• AppWindow pointer needn’t be global
  • Can always be obtained from the DesktopPopupSiteBridge
  • AppWindow can never outlive DesktopPopupSiteBridge
  • No need to check for validity of modalAppWindow as it’d always be true if we’ve a popup bridge
• Drop modal visibility state
  • It’s never separately handled
  • It can always be queried from the AppWindow/Bridge
• Show parent bridge as it wasn’t shown earlier
  • Set a colour for it to be visible
  • Use MoveAndResize to give it a non-trivial size
  • Call Bridge.Show()
• Call UpdateWindow() which usually follows a ShowWindow()
• Call CloseModal() in WM_DESTROY handler as it takes care of checking for popup’s validity