D6: Moved backend pausing to itself

plugins/CuraEngineBackend/CuraEngineBackend.py

@@ -12,6 +12,8 @@ from UM.PluginRegistry import PluginRegistry
 from UM.Resources import Resources
 from UM.Settings.Validator import ValidatorState #To find if a setting is in an error state. We can't slice then.
 from UM.Platform import Platform
+from UM.Scene.Iterator.DepthFirstIterator import DepthFirstIterator
+
 
 import cura.Settings
 
@@ -313,6 +315,26 @@ class CuraEngineBackend(Backend):
         if source is self._scene.getRoot():
             return
 
+        application = Application.getInstance()
+
+        should_pause = False
+        for node in DepthFirstIterator(self._scene.getRoot()):
+            if node.callDecoration("isBlockSlicing"):
+                should_pause = True
+            gcode_list = node.callDecoration("getGCodeList")
+            if gcode_list is not None:
+                self._scene.gcode_list = gcode_list
+
+        print_information = application.getPrintInformation()
+        if should_pause:
+            self.pauseSlicing()
+            if print_information:
+                print_information.setPreSliced(True)
+        else:
+            self.continueSlicing()
+            if print_information:
+                print_information.setPreSliced(False)
+
         if source.getMeshData() is None:
             return