Fix GroupDialog tabs behaviour in OSX.

plugins/uimanager/GroupDialog.cpp

@@ -281,9 +281,6 @@ wxWindow* GroupDialog::addPage(const PagePtr& page)
 	page->page->Reparent(_notebook.get());
 	_notebook->InsertPage(insertPosition, page->page, page->tabLabel, false, imageId);
 
-    // Call Show() on the tab content again, otherwise it ends up invisible in OSX
-    page->page->Show();
-
 	// Add this page by copy to the local list
 	_pages.insert(std::make_pair(page->position, Page(*page)));
 
@@ -318,6 +315,9 @@ void GroupDialog::updatePageTitle(int pageNumber)
 void GroupDialog::onPageSwitch(wxBookCtrlEvent& ev)
 {
 	updatePageTitle(ev.GetSelection());
+
+    // Be sure to skip the event, otherwise pages stay hidden
+    ev.Skip();
 }
 
 } // namespace ui