primitivus: fixed XMLUI window creation

newWidget method was not working if a widget was already selected, breaking all XMLUI with window type.

frontends/src/primitivus/primitivus

@@ -615,8 +615,9 @@ class PrimitivusApp(QuickApp, InputHistory):
 
 
     def newWidget(self, widget):
-        if self.selected_widget is None:
-            self.selectWidget(widget)
+        # FIXME: when several widgets are possible (e.g. with :split)
+        #        do not replace current widget when self.selected_widget != None
+        self.selectWidget(widget)
 
     def selectWidget(self, widget):
         """Display a widget if possible,