diff --git a/src/cells/base.mjs b/src/cells/base.mjs
index 944237a..e0eebc9 100644
--- a/src/cells/base.mjs
+++ b/src/cells/base.mjs
@@ -298,7 +298,8 @@ export const Gate = joint.dia.Element.define('Gate', {
     _gateLayoutParams: ['position'],
     _unsupportedPropChanges: [],
     _operationHelpers: [],
-    _presentationParams: []
+    _presentationParams: [],
+    _gateKind: 'combinational'
 });
 
 export const GateView = joint.dia.ElementView.extend({
diff --git a/src/cells/bus.mjs b/src/cells/bus.mjs
index 6c5169a..0664fc6 100644
--- a/src/cells/bus.mjs
+++ b/src/cells/bus.mjs
@@ -41,7 +41,8 @@ export const BitExtend = Box.define('BitExtend', {
         }
     ]),
     _gateParams: Box.prototype._gateParams.concat(['extend']),
-    _operationHelpers: Box.prototype._operationHelpers.concat(['_extBit'])
+    _operationHelpers: Box.prototype._operationHelpers.concat(['_extBit']),
+    _gateKind: 'bus'
 });
 export const BitExtendView = BoxView.extend({
     _autoResizeBox: true,
@@ -102,7 +103,8 @@ export const BusSlice = Box.define('BusSlice', {
         const s = this.get('slice');
         return { out: data.in.slice(s.first, s.first + s.count) };
     },
-    _gateParams: Box.prototype._gateParams.concat(['slice'])
+    _gateParams: Box.prototype._gateParams.concat(['slice']),
+    _gateKind: 'bus'
 });
 export const BusSliceView = BoxView.extend({
     _autoResizeBox: true
@@ -137,7 +139,8 @@ export const BusRegroup = Box.define('BusRegroup', {
         Box.prototype.initialize.apply(this, arguments);
     },
     _gateParams: Box.prototype._gateParams.concat(['groups']),
-    _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['groups'])
+    _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['groups']),
+    _gateKind: 'bus'
 });
 export const BusRegroupView = BoxView.extend({
     _autoResizeBox: true
diff --git a/src/cells/dff.mjs b/src/cells/dff.mjs
index f908f4d..92dc8b8 100644
--- a/src/cells/dff.mjs
+++ b/src/cells/dff.mjs
@@ -115,7 +115,8 @@ export const Dff = Box.define('Dff', {
         } else return apply_sr(this.get('outputSignals').out);
     },
     _gateParams: Box.prototype._gateParams.concat(['polarity', 'bits', 'initial', 'arst_value', 'srst_value', 'enable_srst', 'no_data']),
-    _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['polarity', 'bits', 'initial', 'arst_value', 'srst_value', 'enable_srst', 'no_data'])
+    _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['polarity', 'bits', 'initial', 'arst_value', 'srst_value', 'enable_srst', 'no_data']),
+    _gateKind: 'stateful'
 });
 export const DffView = BoxView.extend({
     _autoResizeBox: true
diff --git a/src/cells/fsm.mjs b/src/cells/fsm.mjs
index f1d502b..78a39e8 100644
--- a/src/cells/fsm.mjs
+++ b/src/cells/fsm.mjs
@@ -178,7 +178,8 @@ export const FSM = Box.define('FSM', {
     markup: Box.prototype.markup.concat(Box.prototype.markupZoom),
     _gateParams: Box.prototype._gateParams.concat(['bits', 'polarity', 'states', 'init_state', 'trans_table']),
     _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['bits', 'polarity', 'states', 'init_state', 'trans_table']),
-    _presentationParams: Box.prototype._presentationParams.concat(['current_state', 'next_trans'])
+    _presentationParams: Box.prototype._presentationParams.concat(['current_state', 'next_trans']),
+    _gateKind: 'stateful'
 });
 
 export const FSMView = BoxView.extend({
diff --git a/src/cells/memory.mjs b/src/cells/memory.mjs
index fce4f24..fb7f101 100644
--- a/src/cells/memory.mjs
+++ b/src/cells/memory.mjs
@@ -257,7 +257,8 @@ export const Memory = Box.define('Memory', {
     },
     _gateParams: Box.prototype._gateParams.concat(['bits', 'abits', 'rdports', 'wrports', 'words', 'offset']),
     _unsupportedPropChanges: Box.prototype._unsupportedPropChanges.concat(['bits', 'abits', 'rdports', 'wrports', 'words', 'offset']),
-    _operationHelpers: Box.prototype._operationHelpers.concat(['_memrdports', '_memwrports', '_memports', '_calcaddr'])
+    _operationHelpers: Box.prototype._operationHelpers.concat(['_memrdports', '_memwrports', '_memports', '_calcaddr']),
+    _gateKind: 'stateful'
 });
 export const MemoryView = BoxView.extend({
     _autoResizeBox: true,
diff --git a/src/circuit.mjs b/src/circuit.mjs
index 90c7c08..0692a9d 100644
--- a/src/circuit.mjs
+++ b/src/circuit.mjs
@@ -70,8 +70,9 @@ export function getCellType(tp) {
 }
         
 export class HeadlessCircuit {
-    constructor(data, {cellsNamespace = {}, engine = SynchEngine, engineOptions = {}} = {}) {
+    constructor(data, {cellsNamespace = {}, engine = SynchEngine, engineOptions = {}, defaultCombinationalPropagation} = {}) {
         this._cells = Object.assign(cells, cellsNamespace);
+        this._defaultCombinationalPropagation = defaultCombinationalPropagation;
         this._display3vl = new Display3vl();
         this._display3vl.addDisplay(new help.Display3vlASCII());
         this._graph = this._makeGraph(data, data.subcircuits);
@@ -161,6 +162,8 @@ export class HeadlessCircuit {
             cellArgs.id = devid;
             if (cellType == this._cells.Subcircuit)
                 cellArgs.graph = this._makeGraph(subcircuits[dev.celltype], subcircuits, { nested: true });
+            if (this._defaultCombinationalPropagation !== undefined && !('propagation' in cellArgs) && cellType.prototype._gateKind == 'combinational')
+                cellArgs.propagation = this._defaultCombinationalPropagation;
             const cell = new cellType(cellArgs);
             graph.addCell(cell);
         }