Fixed wxMDIChildWindow to be a native window on Mac. Otherwise, functions like SetSize would crash.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@28053 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mac/carbon/mdi.cpp

@@ -368,14 +368,8 @@ wxMDIClientWindow::~wxMDIClientWindow()
 
 bool wxMDIClientWindow::CreateClient(wxMDIParentFrame *parent, long style)
 {
-    
+    if ( !wxWindow::Create(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, style))
-    m_windowId = (int)NewControlId();
+        return FALSE;
-    
-    if ( parent )
-    {
-        parent->AddChild(this);
-    }
-    m_backgroundColour = wxSystemSettings::GetColour(wxSYS_COLOUR_APPWORKSPACE);
     
     wxModelessWindows.Append(this);
     return TRUE;