diff --git a/web/src/designer/FormDesigner.vue b/web/src/designer/FormDesigner.vue
index f6fe933..d49839b 100644
--- a/web/src/designer/FormDesigner.vue
+++ b/web/src/designer/FormDesigner.vue
@@ -38,6 +38,8 @@ const emit = defineEmits<{
   update: [designerText: string, codeText?: string]
   /** 跳到窗体代码文件的某一行 */
   openCode: [line: number]
+  /** 查看设计器生成的 Designer.cs */
+  openDesignerFile: []
   undo: []
   redo: []
 }>()
@@ -431,6 +433,9 @@ const noop = () => {}
         <button :disabled="!canUndo" title="撤销（Ctrl+Z）" @click="emit('undo')">↶ 撤销</button>
         <button :disabled="!canRedo" title="重做（Ctrl+Y）" @click="emit('redo')">↷ 重做</button>
         <span class="tips">拖动工具箱里的控件到窗体上；双击控件生成事件处理方法；Delete 删除</span>
+        <button class="view-code" title="设计器根据窗体上的控件自动生成的代码（Designer.cs）" @click="emit('openDesignerFile')">
+          查看生成的代码
+        </button>
       </div>
       <div class="window" :class="{ selected: selected === '' }">
         <div class="titlebar" @pointerdown="selected = ''">
@@ -581,6 +586,10 @@ const noop = () => {}
   cursor: default;
 }
 
+.view-code {
+  margin-left: auto;
+}
+
 .tips {
   min-width: 0;
   margin-left: 8px;
diff --git a/web/src/pages/WorkbenchPage.vue b/web/src/pages/WorkbenchPage.vue
index 7247fab..7d0d68e 100644
--- a/web/src/pages/WorkbenchPage.vue
+++ b/web/src/pages/WorkbenchPage.vue
@@ -35,14 +35,18 @@ const forms = computed(() => {
     // 启动窗体排在最前
     .sort((a, b) => Number(b.code === `${startup}.cs`) - Number(a.code === `${startup}.cs`))
 })
-/** 标签页按窗体分组：每个窗体依次是 [设计]、代码、Designer.cs；其他文件（Program.cs 等）放最后 */
+/**
+ * 标签页按窗体分组：每个窗体依次是 [设计]、代码；其他文件（Program.cs 等）放最后。
+ * Designer.cs 由设计器生成，平时不显示（和 VS 里藏在窗体文件下面一样），
+ * 在设计器里点"查看生成的代码"或点到其中的编译错误时才临时出现，切走后收起。
+ */
 const tabs = computed(() => {
   const grouped = new Set(forms.value.flatMap((f) => [f.code, f.designer]))
   return [
     ...forms.value.flatMap((f) => [
       { name: f.tab, label: `${f.code} [设计]` },
       { name: f.code, label: f.code },
-      { name: f.designer, label: f.designer },
+      ...(activeTab.value === f.designer ? [{ name: f.designer, label: f.designer }] : []),
     ]),
     ...files.value.filter((f) => !grouped.has(f.path)).map((f) => ({ name: f.path, label: f.path })),
   ]
@@ -308,6 +312,7 @@ function run() {
           @undo="designerHistory.undo(activeForm.designer, activeForm.code)"
           @redo="designerHistory.redo(activeForm.designer, activeForm.code)"
           @open-code="openCode"
+          @open-designer-file="activeTab = activeForm.designer"
         />
         <CodeEditor
           v-show="!activeForm"