Clicking a line separator in the menu closes the menu

Description

Repros in 5.16, 5.17 & 5.18 on desktop app as well as webapp

Steps:
1 - Click the ☰ menu and click the separator line between any two menu items

Expected: The menu doesn't close allowing you to realize you accidentally missed the menu item you were aiming for
Observed: The menu closes without any indication that you miss-clicked

Note: Observed the same behavior on the … ellipsis menu in a message

QA Test Steps

The testing area for this issue is the Dropdown menu/UI/LHS

1. Click on the hamburguer menu
2. Click on the divider and around
3. The menu should remains open

Mana

None

Assignee

Mario de Frutos

QA Assignee

Steve Mudie

Reporter

Steve Mudie

Epic Link

None

Fix versions

Mattermost Team

Platform

Sprint

None

Labels

None

QA Testing Areas

Other (write in QA test steps)

GitHub Issue

None

Components

None

Severity

None
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