WordPress Admin Menu Overlaps widget

I noticed that this widget has some z-index problems that causes the widget to “underlap” the wordpress side admin menu. it kinda stinks, especially when trying to add content to a widget that is in the left column of the defined widget areas on a smaller screen. the user cannot see some of the buttons and some of the content because the visual editor widget goes underneath the wordpress side menu.

https://ww.wp.xz.cn/plugins/black-studio-tinymce-widget/