Invalidate wxDataViewCtrl bests widths on expand/collapse.

The best column widths are computed from "realized" items that are
available as rows in wxDataViewCtrl. This information changes when a
previously collapsed node is expanded and new items become available for
column width calculation.

Fixes #14167.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71334 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/datavgen.cpp

@@ -5082,14 +5082,20 @@ void wxDataViewCtrl::Expand( const wxDataViewItem & item )
 
     int row = m_clientArea->GetRowByItem( item );
     if (row != -1)
+    {
         m_clientArea->Expand(row);
+        InvalidateColBestWidths();
+    }
 }
 
 void wxDataViewCtrl::Collapse( const wxDataViewItem & item )
 {
     int row = m_clientArea->GetRowByItem( item );
     if (row != -1)
+    {
         m_clientArea->Collapse(row);
+        InvalidateColBestWidths();
+    }
 }
 
 bool wxDataViewCtrl::IsExpanded( const wxDataViewItem & item ) const