[Bug]: Side panel new layout: UX is much worse comparing to old layout

[contributor]

New side panel has replaced dedicated buttons with drop-down - without any benefits.

New layout has two major issues:

• it is no longer possible to double click "Document Outline" button to expand/collapse the outline
• it requires two clicks instead of one to toggle between Outline/Thumbnails

Here is new layout (from Firefox):

Here is old layout (from another project):

I find it hard to find even one case where new layout would be better

Web browser and its version

Firefox 148.0

Operating system and its version

Windows 11

PDF.js version

v5.4.624

Is the bug present in the latest PDF.js version?

Yes

Is a browser extension

No

Steps to reproduce the problem

Open any document/book with outline/toc

What is the expected behavior?

• Easy way to expand/collapse document outline
• One click way to switch between outline/thumbnails

What went wrong?

New layout is hardly usable. I cannot longer use Firefox as PDF reader

Link to a viewer

No response

Additional context

No response

[Rob--W]

I reported the same regression with more details (and STR) in https://bugzilla.mozilla.org/show_bug.cgi?id=2019550

For context, the functionality was originally added in #6242
It became unavailable due to the button being moved into a submenu by #20495

There is no sign of this being an intentional change. In retrospect I should perhaps have added unit tests back then. The functionality survived for 10 years without unit tests 😅

[Snuffleupagus]

I reported the same regression with more details (and STR) in https://bugzilla.mozilla.org/show_bug.cgi?id=2019550
[...]
It became unavailable due to the button being moved into a submenu by #20495

A similar bug also affects the "Layers" view in the sidebar, since prior to the mentioned PR it was possible to reset the layers to their initial visibility state by double-clicking on the "Layers" button.

[Rob--W]

And because it is relevant, copying https://bugzilla.mozilla.org/show_bug.cgi?id=2019550#c3 here:

Note that the original flow was documented at https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#outline-sidebar :

• To expand/collapse all items under the selected item, press Shift while clicking on the triangle.
• Double-click on the "Show document outline" button (Show document outline) to expand/collapse all outline items.

Right now, when I Shift-click in the outline, the whole outline collapses, not just the section underneath. That is a bug... It should only collapse the outlines under the section.

And to deal with the regression reported here, an option could be to introduce an artificial top-level triangle, extra buttons, or something else.

[calixteman]

The sidebar has been redesigned by the UX/UI team and it's conform to their specifications.
I wasn't aware of this feature so I didn't notice I broke it.
I'll raise the issue to the UX/UI team.

[contributor]

The sidebar has been redesigned by the UX/UI team and it's conform to their specifications. I wasn't aware of this feature so I didn't notice I broke it. I'll raise the issue to the UX/UI team.

Thanks. What about one click switch?

[calixteman]

The functionality survived for 10 years without unit tests 😅

10 years ago, there weren't the integration tests.
We should add more integration tests especially to make sure that we don't regress or regress on purpose these kind of "hidden" features.

[contributor]

There is more two new layout - wasted vertical space (especially on the bottom). For what?

Old layout utilized full vertical space.

[calixteman]

@contributor, so what should we do ? Hire you as UX/UI designer ? or ask you every time we want to change something ?

The recent changes have been made in order to fit the design specifications provided by our UX/UI team and trust me, these people know what they're doing: they're smart and professional, so if they decided that we must reduce the height of the sidebar it's because they've some good reasons and it isn't absolutely a matter of "it's nicer like this or like that"...
Anyway whatever the choices we make, some people will like them and some other won't... it's just life: we can't make everybody happy. And we could do whatever you want and believe me, some people (other than you of course) will complain.
Anyway, I raised the issues you mentioned to the UX/UI team and we're waiting for their feedback.

[contributor]

Anyway, I raised the issues you mentioned to the UX/UI team and we're waiting for their feedback.

Thank you.

[calixteman]

@contributor, sorry if I've been a bit rude, I had the impress that you were using this place to complain whatever thing you dislike.
For the future, please open a new bug/issue for each problem.

[calixteman]

@contributor about the height, I checked the specs and I'm wrong (I was sure I changed it to make it like this and it appears, thx to git blame, that I'm wrong), I'll fix.

[calixteman]

See #20758.