If the message pane is enabled in the main window (i.e. through F8),
whatever’s opened in there gets entirely reloaded when switching tabs.

For example:

• open a long message in the message pane (if you don’t have one,
  you can save one as a draft with several paragraphs of pseudo-text).
• in the message pane, scroll down to the end of that message;
  you can also enable caret navigation (F7) and move the cursor downwards,
  or select any fragment of the message;
• switch to another tab, e.g. by opening the Calendar tab with Ctrl-Shift-C;
• switch back to the main tab, either through Ctrl-Tab or with Ctrl-W.

As the message pane gets reloaded, you’ll be brought back to the message’s
beginning and therefore lose your previous cursor position, but also any
selection or vertical scroll position.

This is justified by the way that pane is drawn internally (and it’s been
that way for as long as I can remember, so that’s not a new behavior),
but it can be perceived as inconsistent with the way other tabs are handled:
when opening several messages in multiple tabs and switching from one to
the next, vertical position, cursor and selection are all retained.

This is particularly annoying from an accessibility point of view, where
users are relying on cursor position for their screen reader and may not
have a comfortable way of skimming through the message to get to where
they were just a second ago.

Unless fixable, at least that behavior should be documented and use of
the message pane should be officially discouraged for users who rely on
keeping track of the caret’s offset.

(clarifying, this didn't start in any recent version)

(In reply to Valentin Villenave from comment #0)

If the message pane is enabled in the main window (i.e. through F8),
whatever’s opened in there gets entirely reloaded when switching tabs.

Of course. That's how it was developed once.

If I'm reading this correctly, Geoff Lankow is currently working on a redesign of the tabs in Bug 1729379.

Reporter, does this still fail for you when using version 102 or newer version?

Confirmed in version 102.3.0.

(In reply to Noé ROBIN from comment #4)

Confirmed in version 102.3.0.

Thanks Valentin and Noé, we intend to fix this in Bug 1729379 (as you can see in "Depends on" field of this bug), planned for the next major release in mid 2023.

Peter, does this reproduce for you?

Hello,
As I see it the main problem when switching tabs is that the focus is not returned to the message content at all. When caret browsing is enabled the cursor position and selection is remembered. When caret browsing is not enabled then the navigation in the message content is handled by screen reader I think. With orca on linux it seems to be working for me.
I am not using preview pane my-self regularly, and these are my results when testing it on demand.

Steps:

• Make sure message pane is enabled in the view menu
• Open another tab such as conversations or calendar
• Use F6 and shift+F6 to navigate to the message list
• Press ctrl+tab to switch tabs until you return back to the message list.
• Notice how focus is moved back to the message list as intended.
• Now navigate to the message content by pressing tab key, make sure the screen reader is in the focus mode
• Enable caret browsing if it's not enabled
• Use arrow keys to position the caret to a different position than the begining of the message content
• Use ctrl+tab to switch tabs until you return back to the original tab with the preview pane displayed.
• Notice that the focus has not returned to the message content and you have to use F6 and shift+F6 to navigate.
• Once the focus is placed to the message content the caret position and selection seems to be remembered.
• This might be tricky as there might be focusable content inside the message such as links

Does this still reporoduce in version 115, due on a few weeks?

Hello,
As I see it the main problem when switching tabs is that the focus is not returned to the message content at all

But is the pane related on tab switch?