[tools] [visualstates] create new state machine does not remove items

src/tools/visualStates_py/gui/treemodel.py

@@ -124,12 +124,12 @@ def removeState(self, state, parent=None):
         if parent is None:
             parent = self.rootNode
         childToBeRemoved = None
-        for s in parent.getChildren(self.rootNode):
+        for s in parent.getChildren():
             if s.id == state.id:
                 childToBeRemoved = s
                 break
 
-        if childToBeRemoved != None:
+        if childToBeRemoved is not None:
             # print('remove child.id:' + str(childToBeRemoved.id))
             parent.removeChild(childToBeRemoved)
             self.layoutChanged.emit()

src/tools/visualStates_py/gui/visualstates.py

@@ -181,6 +181,8 @@ def createMenu(self):
 
     def newAction(self):
         self.automataScene.clearScene()
+        self.treeModel.removeAll()
+
         # create new root state
         self.rootState = State(0, 'root', True)
         self.automataScene.setActiveState(self.rootState)