The section on "Rework of Thunderbird's main messenger window" in the "Adapt to Changes in Thunderbird 103-115" page does not explain the changes and their implications well enough:
It does not remind the reader about the structure of the 3-pane window.
It does not explain in what contexts the phrase mail3PaneWindow was used, which would now see the use of about:3pane
It does not explain the relation between window/window-object (?) renaming and the switch to a single browser element
It does not discuss whether document elements are the same as before or not
It does not link to a reminder of what a browser element is
It has no rough diagram of "before" and "after" structural relations between parts/elements of the main messenger window
It does not explain how the restructuring affects actions such as:
document.getElementById() (what will now fail)
Use of window.top, window.parent etc.
It does not suggest concrete changes to overlays of messenger.xhtml
It does not explain what code one might have used previously, which the four suggested options are a replacement of.
The section on "Rework of Thunderbird's main messenger window" in the "Adapt to Changes in Thunderbird 103-115" page does not explain the changes and their implications well enough:
mail3PaneWindow
was used, which would now see the use ofabout:3pane
document.getElementById()
(what will now fail)window.top
,window.parent
etc.messenger.xhtml