[Libreoffice-bugs] [Bug 141820] Image->Properties->Type->Position drop down list changes in an inconsistent way when anchor is changed.

Sun May 9 11:06:12 UTC 2021

https://bugs.documentfoundation.org/show_bug.cgi?id=141820

--- Comment #7 from Tomasz Sztejka <sztejkat at yahoo.com> ---
First I would like to thank You all for good work. LibreOffice is my work-horse
and having it working perfectly is very important to me.

Back to business.

> What is listed in the "to" depends on what is selected in "vertical". 
> (...) I don't see an easy "fix" for the UI.

Ok, I do understand that now. This is not a bug, but a confusing design of a
user interface. 

As far as I understand it is is a double cascade: change to anchor changes the
possible set of "vertical" options. Since current option is not available, the
other option is selected without a user action. This selected option changes
the available set in the other set, again without a user action.

This cascade may have, I think, up to five levels in any direction, so it will
be hardly possible to try out all combinations by a user.

I have to agree with You that applying any fix in code will be rather tricky. 

I will try now to take two steps:
 A. Figure out what was responsible for the fact that I missed those side
effects as a user.
 B. Figure out what logic is behind the problem and propose some solutions.

------------------------------------
Ad A) I was aware, that changing anchor may change some choices I do have, so I
was looking for them. But since I was looking for what is available, I did not
try to click every possible combination. This is a first element - one can't
see what is possible in place A without making a selection in places B and C.

Next problem is: what places should I observe to notice those side effects?

 1.The image on the right of anchor radios (I did attached a screenshot just in
case)
 2.Changes in any of eight "Position" settings.
 3.Changes in any of four drop-down lists.

Ad 1) I did notice that when my eyes do focus on radio buttons then the image
presenting setting IS in my center of focus, so I can easily notice something
moves there when I change "anchor". I missed however those changes when I was
making selections to "Position" drop downs. 

Ad 2) Those eight "Position" settings are far enough from "anchor" and image so
that they are out of sight and attention focus. They are just text so I missed
they are changing.

Ad 3) Change in possible choices on drop-down list is of course invisible.
X-ray vision is necessary ;)

So the first problem is: the arrangement of GUI is such, that some side effects
are hard or impossible to notice.

The most helping element which is an image which shows what is going on is at
the side, far off from the attention center. To make it even harder it is
logically grouped with "Anchor" and "Size", being in one row, but not in fact
with "Position" which is below.

This is _why_ I didn't notice.

---------------------------------------
Ad B) The big question is: what logic is behind it?

I think the main reason is an _asymmetry_ of a data structure (choices
available in step 2 do depend on choice made in step 1) related to anchoring
and designed _symmetry_ of user interface (all choices available at every step,
selections are independent). Asymmetric is a tree like selection, symmetric is
a table like. In table every combination You can select in any column forms a
valid selection, in tree You have to follow the path.

This is hardly possible to present an asymmetric choice in a symmetric GUI
without a nasty set of side effects. This is exactly what is observed.

In symmetric GUI user may make choices in any order and, as You noticed, some
selections can't be moved from one branch of selection tree to an another one.

I think this is a key point: I did switched the "anchor" and some selection
become "impossible" in this context. Since it was impossible to keep it,
program did some "best choice" behind my back. This triggered a cascade. I
missed that and got confused. 

Now imagine how would this GUI behave if I would start making selection from
the bottom right corner of this dialog and going up? Nothing prevents me from
doing it in that way, but a final effect is, if You try it, almost
unpredictable.

-------------------------------

There are two possible paths of solving it, I think:

1.Make side effect clearly visible.
2.Make "impossible" to become "possible".

Ad 1)

The center of "Anchor" operation is that image on right. It could be put in
center of attention and updated to more precisely present the effect (mirror is
missing now for an example).

The options should be located around it, horizontal at the bottom, vertical on
right, anchors on the left.

Drop down lists should be changed to radio-buttons blocks with grayed out
disabled options so that changes to available choices would be clearly visible.

Tooltips should be added to every element.

Side effect may be left as they are now, they should be much easier to notice.

Ad 2)

First assume following presentation of "impossible" options:

 1.If option is a selection from a drop down list:
  a) show it in RED and striked-out (some can't tell colors apart);
  b) update tooltip to that selection to say "This is impossible in that anchor
mode";

 2.If the option is the value in "by" input field:
  a) leave value as it is;
  b) keep input field enabled and show value as striked-out text;
  b) update tooltip to that selection to say "This value is ignored in that
anchor mode";

 3.If the option is a check-box, then it means that check box has no meaning in
that anchor mode, so:
  a) leave value as it is;
  b) keep it enabled so user may click and change it;
  c) show it as striked-out;
  d) update tooltip to that selection to say "This option is not aplicable in
that anchor mode";

Second:

 1.Always show all options in drop down lists. Those "impossible" in current
context should be shown as impossible, but user must be allowed to select it
anyway. Selection of such an impossible option should disable "OK" button,
because such an option cannot be applied.

 2.Always allow user to click check box, even if not applicable, and type
values in "by" field, even ignored. Simply show them according to their status.
Not applicable/ignored values in check-boxes and input fields should be
silently ignored when user clicks "OK".

Third:

 1. Make tooltips to explain what is what. This will help users to understand
why some option is impossible and how to use it.

Fourth:

 1. The "Anchor" is a main setting. Setting anchor mode is always possible and
it dictates what is possible and what is not, either directly or through a
cascade. No "impossible" presentation here, since otherwise we would have a
logic loop.

Result:

This will:
  a) force user to update their choice to a valid one, so no side effect can
escape their attention;
  b) let user to click back to their previous selection since GUI still
preserves old, "impossible" now settings;
  c) the interface becomes discoverable, because user can always see all
options;
  d) the result does not depend on order of selections. The
right-bottom-corner-up scenario I described above should be now possible and
give reasonable results.

----------------------------------------------------------

Note:Unfortunately when playing I had hit an another bug in the same area:
https://bugs.documentfoundation.org/show_bug.cgi?id=142178

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