fix: can not show slash menu if insert "/" before select block (#2999)

packages/blocks/src/page-block/utils/container-operations.ts

@@ -19,6 +19,7 @@ import {
   focusBlockByModel,
   getBlockElementByModel,
   getClosestBlockElementByElement,
+  getCurrentNativeRange,
   getDefaultPage,
   getVirgoByModel,
   handleNativeRangeDblClick,
@@ -40,6 +41,7 @@ import {
 import { asyncFocusRichText } from '../../__internal__/utils/common-operations.js';
 import { clearMarksOnDiscontinuousInput } from '../../__internal__/utils/virgo.js';
 import { showFormatQuickBar } from '../../components/format-quick-bar/index.js';
+import { showSlashMenu } from '../../components/slash-menu/index.js';
 import type { BlockSchemas } from '../../models.js';
 import type {
   DefaultSelectionManager,
@@ -537,6 +539,14 @@ export function handleKeydownAfterSelectBlocks({
     const newBlock = page.getBlockById(id) as BaseBlockModel;
     defaultPage?.selection.clear();
     focusBlockByModel(newBlock, 'end');
+
+    // XXX: slash menu trigger probably shouldn't be here
+    if (key === '/') {
+      const curRange = getCurrentNativeRange();
+      const model = page.getBlockById(id);
+      assertExists(model);
+      showSlashMenu({ model, range: curRange });
+    }
   });
 }
 export async function onModelTextUpdated(