【Notebook】The focus of the "Menu" button will not disappear

[Liang-zy]

Version: 20.04 LTS
Test environment: ThinkPad X1
Test steps:
Step 1. Open the Notebook
Step 2. Click "Menu", click elsewhere
Expected results:
Step 1. Open Notebook
Step 2. The click event is normal
actual results:
Step 1. Normal
Step 2. It is found that clicking the "menu" will grab the focus