Fixed some issues caused by the multi buildplate system

cura/ObjectsModel.py

@@ -8,6 +8,7 @@ from UM.i18n import i18nCatalog
 
 catalog = i18nCatalog("cura")
 
+
 ##  Keep track of all objects in the project
 class ObjectsModel(ListModel):
     def __init__(self):
@@ -46,10 +47,15 @@ class ObjectsModel(ListModel):
                 name = catalog.i18nc("@label", "Group #{group_nr}").format(group_nr = str(group_nr))
                 group_nr += 1
 
+            if hasattr(node, "isOutsideBuildArea"):
+                is_outside_build_area = node.isOutsideBuildArea()
+            else:
+                is_outside_build_area = False
+
             nodes.append({
                 "name": name,
                 "isSelected": Selection.isSelected(node),
-                "isOutsideBuildArea": node.isOutsideBuildArea(),
+                "isOutsideBuildArea": is_outside_build_area,
                 "buildPlateNumber": node_build_plate_number,
                 "node": node
             })

cura/Scene/CuraSceneController.py

@@ -59,6 +59,8 @@ class CuraSceneController(QObject):
         for node in DepthFirstIterator(Application.getInstance().getController().getScene().getRoot()):
             if node.callDecoration("isSliceable"):
                 build_plate_number = node.callDecoration("getBuildPlateNumber")
+                if build_plate_number is None:
+                    build_plate_number = 0
                 max_build_plate = max(build_plate_number, max_build_plate)
         return max_build_plate
 

plugins/CuraEngineBackend/CuraEngineBackend.py

@@ -187,9 +187,7 @@ class CuraEngineBackend(QObject, Backend):
     ##  Manually triggers a reslice
     @pyqtSlot()
     def forceSlice(self):
-        if self._use_timer:
-            self._change_timer.start()
-        else:
+        self.markSliceAll()
         self.slice()
 
     ##  Perform a slice of the scene.