diff --git a/packages/designer/src/document/history.ts b/packages/designer/src/document/history.ts
index 0f283b65b..8a37f1032 100644
--- a/packages/designer/src/document/history.ts
+++ b/packages/designer/src/document/history.ts
@@ -174,6 +174,10 @@ export class History {
     this.emitter.removeAllListeners();
     this.records = [];
   }
+
+  isModified() {
+    return this.point !== this.session.cursor;
+  }
 }
 
 class Session {
diff --git a/packages/vision-preset/src/index.ts b/packages/vision-preset/src/index.ts
index 23dbe607a..ed632b3ef 100644
--- a/packages/vision-preset/src/index.ts
+++ b/packages/vision-preset/src/index.ts
@@ -25,6 +25,7 @@ import DragEngine from './drag-engine';
 import Viewport from './viewport';
 import Project from './project';
 import { designer, editor } from './editor';
+import Symbols from './symbols';
 
 import './vision.less';
 
@@ -109,6 +110,7 @@ const VisualEngine = {
   Version,
   Project,
   logger,
+  Symbols,
 };
 
 (window as any).VisualEngine = VisualEngine;
@@ -156,6 +158,7 @@ export {
   Version,
   Project,
   logger,
+  Symbols,
 };
 
 
diff --git a/packages/vision-preset/src/symbols.ts b/packages/vision-preset/src/symbols.ts
new file mode 100644
index 000000000..81091e371
--- /dev/null
+++ b/packages/vision-preset/src/symbols.ts
@@ -0,0 +1,17 @@
+export class SymbolManager {
+  private symbolMap: { [symbolName: string]: symbol } = {};
+
+  public create(name: string): symbol {
+    if (this.symbolMap[name]) {
+      return this.symbolMap[name];
+    }
+    this.symbolMap[name] = Symbol(name);
+    return this.symbolMap[name];
+  }
+
+  public get(name: string) {
+    return this.symbolMap[name];
+  }
+}
+
+export default new SymbolManager();