You can now toggle whether decomposed elements are parented in blender when editing, so voids/fills etc move with you.

src/blenderbim/blenderbim/bim/module/model/workspace.py

@@ -28,6 +28,7 @@ class BimTool(WorkSpaceTool):
         ("bim.hotkey", {"type": "V", "value": "PRESS", "shift": True}, {"properties": [("hotkey", "S_V")]}),
         ("bim.hotkey", {"type": "O", "value": "PRESS", "shift": True}, {"properties": [("hotkey", "S_O")]}),
         ("bim.hotkey", {"type": "O", "value": "PRESS", "alt": True}, {"properties": [("hotkey", "A_O")]}),
+        ("bim.hotkey", {"type": "D", "value": "PRESS", "alt": True}, {"properties": [("hotkey", "A_D")]}),
     )
 
     def draw_settings(context, layout, tool):
@@ -88,6 +89,9 @@ class BimTool(WorkSpaceTool):
         row = layout.row(align=True)
         row.label(text="", icon="EVENT_ALT")
         row.label(text="Opening", icon="EVENT_O")
+        row = layout.row(align=True)
+        row.label(text="", icon="EVENT_ALT")
+        row.label(text="Decomposition", icon="EVENT_D")
 
 
 class Hotkey(bpy.types.Operator):
@@ -132,5 +136,8 @@ class Hotkey(bpy.types.Operator):
         elif self.props.ifc_class == "IfcSlabType":
             bpy.ops.bim.add_slab_opening()
 
+    def hotkey_A_D(self):
+        bpy.ops.bim.toggle_decomposition_parenting()
+
     def hotkey_A_O(self):
         bpy.ops.bim.toggle_opening_visibility()

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

@@ -29,7 +29,7 @@ class BIM_PT_class(Panel):
             if props.is_reassigning_class:
                 row = self.layout.row(align=True)
                 row.operator("bim.reassign_class", icon="CHECKMARK")
-                row.operator("bim.disable_reassign_class", icon="X", text="")
+                row.operator("bim.disable_reassign_class", icon="CANCEL", text="")
                 self.draw_class_dropdowns(context)
             else:
                 data = Data.products[props.ifc_definition_id]

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

@@ -7,6 +7,7 @@ classes = (
     operator.AddFilling,
     operator.RemoveFilling,
     operator.ToggleOpeningVisibility,
+    operator.ToggleDecompositionParenting,
     prop.VoidProperties,
     ui.BIM_PT_voids,
 )

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

@@ -142,3 +142,54 @@ class ToggleOpeningVisibility(bpy.types.Operator):
             for collection in [c for c in project.children if "IfcOpeningElements" in c.name]:
                 collection.hide_viewport = not collection.hide_viewport
         return {"FINISHED"}
+
+
+class ToggleDecompositionParenting(bpy.types.Operator):
+    bl_idname = "bim.toggle_decomposition_parenting"
+    bl_label = "Toggle Decomposition Parenting"
+    bl_options = {"REGISTER", "UNDO"}
+    obj: bpy.props.StringProperty()
+
+    def execute(self, context):
+        obj = bpy.data.objects.get(self.obj) if self.obj else context.active_object
+        self.file = IfcStore.get_file()
+        is_parenting = None
+
+        self.decompositions = {}
+        self.load_decompositions(obj)
+
+        for parent, children in self.decompositions.items():
+            bpy.ops.bim.dynamically_void_product(obj=parent.name)
+            for child in children:
+                bpy.ops.bim.dynamically_void_product(obj=child.name)
+                if is_parenting is None:
+                    is_parenting = not bool(child.parent)
+
+                if is_parenting:
+                    child.parent = parent
+                    child.matrix_parent_inverse = parent.matrix_world.inverted()
+                else:
+                    parent_matrix_world = child.matrix_world.copy()
+                    child.parent = None
+                    child.matrix_world = parent_matrix_world
+
+        return {"FINISHED"}
+
+    def load_decompositions(self, parent_obj):
+        element = self.file.by_id(parent_obj.BIMObjectProperties.ifc_definition_id)
+        for rel in self.file.get_inverse(element):
+            if not (rel.is_a("IfcRelDecomposes") or rel.is_a("IfcRelFillsElement")):
+                continue
+            if rel[4] != element:
+                continue
+            if isinstance(rel[5], tuple):
+                for related_object in rel[5]:
+                    self.add_decomposition(parent_obj, related_object)
+            else:
+                self.add_decomposition(parent_obj, rel[5])
+
+    def add_decomposition(self, parent_obj, child_element):
+        child_obj = IfcStore.get_element(child_element.id())
+        if child_obj:
+            self.decompositions.setdefault(parent_obj, []).append(child_obj)
+            self.load_decompositions(child_obj)