lokdialog: Show/Hide floating window on StateChangedType::Visible

In the earlier approach, other state change events like SetText are
emitted which ends up in "else if !IsVisible()" block and tries to close
the floating window before it's even registered.

Interestingly, this is not the case every time. Anyhow, better safe than
sorry. Guard the floating window 'created', 'close' callbacks in a
StateChangeType::Visible event.

Change-Id: Ib997e11fd4a0f50b8911e9891918112e8ff8ef85

vcl/source/window/floatwin.cxx

@@ -603,11 +603,12 @@ void FloatingWindow::StateChanged( StateChangedType nType )
 
     SystemWindow::StateChanged( nType );
 
-    if (VclPtr<vcl::Window> pParent = GetParentWithLOKNotifier())
+    VclPtr<vcl::Window> pParent = GetParentWithLOKNotifier();
+    if (pParent && nType == StateChangedType::Visible)
     {
-        const vcl::ILibreOfficeKitNotifier* pNotifier = pParent->GetLOKNotifier();
-        if (nType == StateChangedType::InitShow && IsVisible())
+        if (IsVisible())
         {
+            const vcl::ILibreOfficeKitNotifier* pNotifier = pParent->GetLOKNotifier();
             SetLOKNotifier(pNotifier);
 
             std::vector<vcl::LOKPayloadItem> aItems;
@@ -619,7 +620,8 @@ void FloatingWindow::StateChanged( StateChangedType nType )
         }
         else if (!IsVisible())
         {
-            pNotifier->notifyWindow(GetLOKWindowId(), "close");
+            assert(GetLOKNotifier());
+            GetLOKNotifier()->notifyWindow(GetLOKWindowId(), "close");
             ReleaseLOKNotifier();
         }
     }