Factor out wxTopLevelWindowGTK::GTKDoAfterShow()

Just extract the code generating wxEVT_SHOW for TLWs in wxGTK in its own
function before modifying it to avoid having to do it in two places.

No real changes, this is a pure refactoring.

include/wx/gtk/toplevel.h

@@ -136,6 +136,8 @@ public:
 
     void GTKUpdateDecorSize(const DecorSize& decorSize);
 
+    void GTKDoAfterShow();
+
 protected:
     // give hints to the Window Manager for how the size
     // of the TLW can be changed by dragging

src/gtk/toplevel.cpp

@@ -445,9 +445,7 @@ gtk_frame_map_callback( GtkWidget*,
     // it is possible for m_isShown to be false here, see bug #9909
     if (win->wxWindowBase::Show(true))
     {
-        wxShowEvent eventShow(win->GetId(), true);
-        eventShow.SetEventObject(win);
-        win->GetEventHandler()->ProcessEvent(eventShow);
+        win->GTKDoAfterShow();
     }
 
     // restore focus-on-map setting in case ShowWithoutActivating() was called
@@ -1499,9 +1497,8 @@ void wxTopLevelWindowGTK::GTKUpdateDecorSize(const DecorSize& decorSize)
             SendSizeEvent();
         }
 #endif
-        wxShowEvent showEvent(GetId(), true);
-        showEvent.SetEventObject(this);
-        HandleWindowEvent(showEvent);
+
+        GTKDoAfterShow();
     }
 #endif // GDK_WINDOWING_X11
 }
@@ -1523,6 +1520,13 @@ wxTopLevelWindowGTK::DecorSize& wxTopLevelWindowGTK::GetCachedDecorSize()
     return size[index];
 }
 
+void wxTopLevelWindowGTK::GTKDoAfterShow()
+{
+    wxShowEvent showEvent(GetId(), true);
+    showEvent.SetEventObject(this);
+    HandleWindowEvent(showEvent);
+}
+
 // ----------------------------------------------------------------------------
 // frame title/icon
 // ----------------------------------------------------------------------------