TB v 102.0.3 addon MoreLayouts 7.1 causes double vertical scrollbar

Feed back for addon ‘More Layouts’ version 7.1
Using Windows 10 OS
Thunderbird version 102.0.3

Set: View > Headers > All
Enable Message Pane

There is a splitter bar top separating top edge of actual message from bottom of header. This is created by this addon.

It is possible to Move height of email header area up by grab/drag bottom of header area but it is causing unusual display for scrollbar which becomes two vertical scrollbar - side by side.

It is also possible to pull down the bottom of header so it is reveals a blank area in header zone as scrollbar does not extend.

By default in Thunderbird there is no ability to grab a splitter and increase the height of the header area. As it exists when using addon, it would be good for it to have more control over the vertical scrollbar, so extending area also extends scrollbar and reducing area does not cause a double vertical scrollbar.