Add missing index initialization in one of wxEnumProperty ctor.

In every wxEnumProperty ctor, initial index value of selected choice must be set to zero.

See #16401.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76993 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/propgrid/props.cpp

@@ -1159,6 +1159,8 @@ wxEnumProperty::wxEnumProperty( const wxString& label, const wxString& name,
     wxPGChoices& choices, int value )
     : wxPGProperty(label,name)
 {
+    SetIndex(0);
+
     m_choices.Assign( choices );
 
     if ( GetItemCount() )