About this Add-on
This will add the button to open or close the Message Pane, without extra buttons you do not want or need.
After installing and restarting, just need to Customize the toolbar and then drag the icon/button to the toolbar.
To create your own collections, you must have a Mozilla Add-ons account.
Some add-ons ask for permission to perform certain functions. Since you’re in control of your Firefox, the choice to grant or deny these requests is yours.
Please note this add-on uses legacy technology, which gives it access to all browser functions and data without requesting your permission.