Factor out wxGenericTreeCtrl::InitVisualAttributes()

No real changes, just avoid calling an event handler directly.

include/wx/generic/treectlg.h

@@ -354,7 +354,14 @@ protected:
 private:
     bool m_hasExplicitFont;
 
-    void OnSysColourChanged(wxSysColourChangedEvent&);
+    void OnSysColourChanged(wxSysColourChangedEvent& WXUNUSED(event))
+    {
+        InitVisualAttributes();
+    }
+
+    // (Re)initialize colours, fonts, pens, brushes used by the control using
+    // the current system colours and font.
+    void InitVisualAttributes();
 
     // Reset the state of the last find (i.e. keyboard incremental search)
     // operation.

src/generic/treectlg.cpp

@@ -983,8 +983,7 @@ bool wxGenericTreeCtrl::Create(wxWindow *parent,
     }
 
     m_hasExplicitFont = m_hasFont;
-    wxSysColourChangedEvent evt;
-    OnSysColourChanged(evt);
+    InitVisualAttributes();
 
     SetInitialSize(size);
 
@@ -1007,7 +1006,7 @@ void wxGenericTreeCtrl::EnableBellOnNoMatch( bool on )
     m_findBell = on;
 }
 
-void wxGenericTreeCtrl::OnSysColourChanged(wxSysColourChangedEvent&)
+void wxGenericTreeCtrl::InitVisualAttributes()
 {
     const wxVisualAttributes attr(GetDefaultAttributes());
     SetOwnForegroundColour(attr.colFg);