Activate the view of a newly created document.

This appears to be necessary under Mac where views are top level windows and
should do no harm elsewhere.

Also factor out the activation code in a new wxDocManager::ActivateDocument()
method to avoid duplicating it.

Closes #11417.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64440 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/docview.h

@@ -501,6 +501,9 @@ protected:
     // view and returns it then
     wxView *GetActiveView() const;
 
+    // activate the first view of the given document if any
+    void ActivateDocument(wxDocument *doc);
+
 
     int               m_defaultDocumentNameCounter;
     int               m_maxDocsOpen;