You can now toggle expansion of the cost item tree

src/blenderbim/blenderbim/bim/module/cost/__init__.py

@@ -8,6 +8,8 @@ classes = (
     operator.EnableEditingCostSchedule,
     operator.DisableEditingCostSchedule,
     operator.AddCostItem,
+    operator.ExpandCostItem,
+    operator.ContractCostItem,
     prop.CostItem,
     prop.BIMCostProperties,
     ui.BIM_PT_cost_schedules,

src/blenderbim/blenderbim/bim/module/cost/operator.py

@@ -65,6 +65,7 @@ class EnableEditingCostSchedule(bpy.types.Operator):
         while len(self.props.cost_items) > 0:
             self.props.cost_items.remove(0)
 
+        self.contracted_cost_items = json.loads(self.props.contracted_cost_items)
         for related_object_id in Data.cost_schedules[self.cost_schedule]["RelatedObjects"]:
             self.create_new_cost_item_li(related_object_id, 0)
         return {"FINISHED"}
@@ -74,12 +75,13 @@ class EnableEditingCostSchedule(bpy.types.Operator):
         new = self.props.cost_items.add()
         new.name = cost_item["Name"] or "Unnamed"
         new.ifc_definition_id = related_object_id
-        new.is_expanded = False
+        new.is_expanded = related_object_id not in self.contracted_cost_items
         new.level_index = level_index
         if cost_item["RelatedObjects"]:
             new.has_children = True
-            for related_object_id in cost_item["RelatedObjects"]:
-                self.create_new_cost_item_li(related_object_id, level_index + 1)
+            if new.is_expanded:
+                for related_object_id in cost_item["RelatedObjects"]:
+                    self.create_new_cost_item_li(related_object_id, level_index + 1)
 
 
 class DisableEditingCostSchedule(bpy.types.Operator):
@@ -134,3 +136,31 @@ class AddCostItem(bpy.types.Operator):
         Data.load(self.file)
         bpy.ops.bim.enable_editing_cost_schedule(cost_schedule = self.cost_schedule)
         return {"FINISHED"}
+
+
+class ExpandCostItem(bpy.types.Operator):
+    bl_idname = "bim.expand_cost_item"
+    bl_label = "Expand Cost Item"
+    cost_item: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMCostProperties
+        contracted_cost_items = json.loads(props.contracted_cost_items)
+        contracted_cost_items.remove(self.cost_item)
+        props.contracted_cost_items = json.dumps(contracted_cost_items)
+        bpy.ops.bim.enable_editing_cost_schedule(cost_schedule = props.active_cost_schedule_id)
+        return {"FINISHED"}
+
+
+class ContractCostItem(bpy.types.Operator):
+    bl_idname = "bim.contract_cost_item"
+    bl_label = "Contract Cost Item"
+    cost_item: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMCostProperties
+        contracted_cost_items = json.loads(props.contracted_cost_items)
+        contracted_cost_items.append(self.cost_item)
+        props.contracted_cost_items = json.dumps(contracted_cost_items)
+        bpy.ops.bim.enable_editing_cost_schedule(cost_schedule = props.active_cost_schedule_id)
+        return {"FINISHED"}

src/blenderbim/blenderbim/bim/module/cost/prop.py

@@ -26,3 +26,4 @@ class BIMCostProperties(PropertyGroup):
     active_cost_schedule_id: IntProperty(name="Active Cost Schedule Id")
     cost_items: CollectionProperty(name="Work Calendar", type=CostItem)
     active_cost_item_index: IntProperty(name="Active Cost Item Index")
+    contracted_cost_items: StringProperty(name="Contracted Cost Items", default="[]")

src/blenderbim/blenderbim/bim/module/cost/ui.py

@@ -72,9 +72,10 @@ class BIM_UL_cost_items(UIList):
                 row.label(text="", icon="BLANK1")
             if item.has_children:
                 if item.is_expanded:
-                    row.operator("bim.edit_work_calendar", text="", emboss=False, icon="DISCLOSURE_TRI_DOWN")
+                    op = row.operator("bim.contract_cost_item", text="", emboss=False, icon="DISCLOSURE_TRI_DOWN")
                 else:
-                    row.operator("bim.edit_work_calendar", text="", emboss=False, icon="DISCLOSURE_TRI_RIGHT")
+                    op = row.operator("bim.expand_cost_item", text="", emboss=False, icon="DISCLOSURE_TRI_RIGHT")
+                op.cost_item = item.ifc_definition_id
             else:
                 row.label(text="", icon="DOT")
             row.label(text=item.name)