diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index 7507f48a..6aaaf477 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -11,8 +11,7 @@ const { newPoint, newPolygon } = base;
 const { driver } = kiri;
 const { CAM } = driver;
 
-let PRO = CAM.process,
-    isAnimate,
+let isAnimate,
     isArrange,
     isCamMode,
     isParsed,
@@ -568,20 +567,29 @@ CAM.init = function(kiri, api) {
         func.traceDone();
         func.surfaceDone();
         alert = api.show.alert("analyzing surfaces...", 1000);
-        CAM.surfaces(data => {
+        let surfaces = poppedRec.surfaces;
+        CAM.surfaces(() => {
             api.hide.alert(alert);
             alert = api.show.alert("[esc] cancels surface editing");
+            for (let [wid, arr] of Object.entries(surfaces)) {
+                let widget = api.widgets.forid(wid);
+                if (widget && arr.length)
+                for (let faceid of arr) {
+                    CAM.surface_toggle(widget, faceid, faceids => {
+                        // surfaces[widget.id] = faceids;
+                    });
+                }
+            }
         });
         surfaceOn = hoveredOp;
         surfaceOn.classList.add("editing");
         api.feature.on_mouse_up = (obj, ev) => {
             let { face } = obj;
             let min = Math.min(face.a, face.b, face.c);
+            let faceid = min / 3;
             let widget = lastWidget = obj.object.widget;
-            CAM.surface_find(widget.id, min / 3, faces => {
-                if (faces && faces.length) {
-                    widget.selectFaces(faces);
-                }
+            CAM.surface_toggle(widget, faceid, faceids => {
+                surfaces[widget.id] = faceids;
             });
         };
     };
@@ -589,7 +597,12 @@ CAM.init = function(kiri, api) {
         if (!surfaceOn) {
             return;
         }
-        lastWidget.selectFaces([]);
+        if (lastWidget) {
+            let surfaces = poppedRec.surfaces;
+            for (let wid of Object.keys(surfaces)) {
+                CAM.surface_clear(api.widgets.forid(wid));
+            }
+        }
         api.hide.alert(alert);
         api.feature.on_mouse_up = undefined;
         surfaceOn.classList.remove("editing");
diff --git a/src/kiri-mode/cam/driver.js b/src/kiri-mode/cam/driver.js
index 28fb68f5..1078baa5 100644
--- a/src/kiri-mode/cam/driver.js
+++ b/src/kiri-mode/cam/driver.js
@@ -24,68 +24,88 @@ CAM.process = {
 // defer loading until kiri.client and kiri.worker exist
 kiri.load(api => {
 
-    if (kiri.client)
-    CAM.traces = function(ondone, single) {
-        kiri.client.sync();
-        const settings = api.conf.get();
-        const widgets = api.widgets.map();
-        kiri.client.send("cam_traces", { settings, single }, output => {
-            const ids = [];
-            kiri.codec.decode(output).forEach(rec => {
-                ids.push(rec.id);
-                widgets[rec.id].traces = rec.traces;
+    if (kiri.client) {
+        CAM.surfaces = function(ondone) {
+            kiri.client.sync();
+            const settings = api.conf.get();
+            kiri.client.send("cam_surfaces", { settings }, output => {
+                ondone(output);
             });
-            ondone(ids);
-        });
-    };
+        };
 
-    if (kiri.worker)
-    kiri.worker.cam_traces = function(data, send) {
-        const { settings, single } = data;
-        const widgets = Object.values(kiri.worker.cache);
-        const fresh = widgets.filter(widget => CAM.traces(settings, widget, single));
-        send.done(kiri.codec.encode(fresh.map(widget => { return {
-            id: widget.id,
-            traces: widget.traces,
-        } } )));
-    };
+        function select_face_groups(widget) {
+            widget.selectFaces(Object.values(widget._surfaces).flat());
+        };
 
-    if (kiri.client)
-    CAM.surfaces = function(ondone) {
-        kiri.client.sync();
-        const settings = api.conf.get();
-        kiri.client.send("cam_surfaces", { settings }, output => {
-            ondone(output);
-        });
-    };
-
-    if (kiri.worker)
-    kiri.worker.cam_surfaces = function(data, send) {
-        const { settings } = data;
-        const widgets = Object.values(kiri.worker.cache);
-        for (let widget of widgets) {
-            if (!widget.tool) {
-                let tool = widget.tool = new mesh.tool();
-                tool.generateFaceMap(widget.getVertices().array);
+        CAM.surface_toggle = function(widget, face, ondone) {
+            let surfaces = widget._surfaces = widget._surfaces || {};
+            for (let [root, faces] of Object.entries(surfaces)) {
+                if (faces.contains(face)) {
+                    // delete this face group
+                    delete surfaces[root];
+                    select_face_groups(widget);
+                    ondone(Object.keys(surfaces));
+                    return;
+                }
             }
+            kiri.client.send("cam_surface_find", { id: widget.id, face }, faces => {
+                surfaces[face] = faces;
+                select_face_groups(widget);
+                ondone(Object.keys(surfaces));
+            });
+        };
+
+        CAM.surface_clear = function(widget) {
+            widget.selectFaces([]);
+            widget._surfaces = {};
+        };
+
+        CAM.traces = function(ondone, single) {
+            kiri.client.sync();
+            const settings = api.conf.get();
+            const widgets = api.widgets.map();
+            kiri.client.send("cam_traces", { settings, single }, output => {
+                const ids = [];
+                kiri.codec.decode(output).forEach(rec => {
+                    ids.push(rec.id);
+                    widgets[rec.id].traces = rec.traces;
+                });
+                ondone(ids);
+            });
+        };
+    }
+
+    if (kiri.worker) {
+        kiri.worker.cam_surfaces = function(data, send) {
+            const { settings } = data;
+            const widgets = Object.values(kiri.worker.cache);
+            for (let widget of widgets) {
+                if (!widget.tool) {
+                    let tool = widget.tool = new mesh.tool();
+                    tool.generateFaceMap(widget.getVertices().array);
+                }
+            }
+            send.done({});
+        };
+
+        kiri.worker.cam_surface_find = function(data, send) {
+            const { id, face } = data;
+            const widget = kiri.worker.cache[id];
+            const faces = widget.tool.findConnectedSurface([face], 0.1, 0.001);
+            send.done(faces);
         }
-        send.done({});
-    };
 
-    if (kiri.client)
-    CAM.surface_find = function(id, face, ondone) {
-        kiri.client.send("cam_surface_find", { id, face }, faces => {
-            ondone(faces);
-        });
-    };
+        kiri.worker.cam_traces = function(data, send) {
+            const { settings, single } = data;
+            const widgets = Object.values(kiri.worker.cache);
+            const fresh = widgets.filter(widget => CAM.traces(settings, widget, single));
+            send.done(kiri.codec.encode(fresh.map(widget => { return {
+                id: widget.id,
+                traces: widget.traces,
+            } } )));
+        };
+    }
 
-    if (kiri.worker)
-    kiri.worker.cam_surface_find = function(data, send) {
-        const { id, face } = data;
-        const widget = kiri.worker.cache[id];
-        const faces = widget.tool.findConnectedSurface([face], 0.1, 0.001);
-        send.done(faces);
-    };
 });
 
 });
diff --git a/src/kiri/widgets.js b/src/kiri/widgets.js
index 81a353b7..bcf6a500 100644
--- a/src/kiri/widgets.js
+++ b/src/kiri/widgets.js
@@ -110,6 +110,7 @@ const widgets = api.widgets = {
     count()     { return WIDGETS.length },
     each(fn)    { WIDGETS.slice().forEach(widget => fn(widget)) },
     for(fn)     { widgets.each(fn) },
+    forid(id)   { return WIDGETS.filter(w => w.id === id)[0] }
 };
 
 });