Dragging a combo hides edges

[bartoval]

Describe the bug / 问题描述

when you enable the drag-element behavior and drag a combo, every link connected to its nodes is obscured by the layout of the combo, as if it had a lower z-index".

Reproduction link / 重现链接

No response

Steps to Reproduce the Bug or Issue / 重现步骤

1. it is possible to verify this behavior in the playground -> custom combo -> extra box by adding a background to the combo for example: combos: [{ id: 'combo-0', style:{fill:'red', fillOpacity:1 }}],

2. then drag the combo

G6 Version / G6 版本

🆕 5.x

Operating System / 操作系统

Linux

Browser / 浏览器

Chrome

Additional context / 补充说明

No response