Bug 120282

Summary:	Form element List Box should disable its Multiselection option, if Dropdown option is set to Yes
Product:	LibreOffice	Reporter:	Buovjaga <ilmari.lauhakangas>
Component:	UI	Assignee:	Not Assigned <libreoffice-bugs>
Status:	NEW ---
Severity:	enhancement	CC:	c_strobbe-fdo, xiscofauli
Priority:	low
Version:	Inherited From OOo
Hardware:	All
OS:	All
See Also:	https://bugs.documentfoundation.org/show_bug.cgi?id=72932
Whiteboard:
Crash report or crash signature:		Regression By:
Bug Depends on:
Bug Blocks:	107742

Description Buovjaga 2018-10-03 11:45:06 UTC

Inspired by bug 72932.

A dropdown UI element by design is for picking a single item. We should not mislead users into thinking otherwise.

1. View - Toolbars - Form controls
2. Draw a List Box and configure it
3. Right-click - Control
4. Play around with the options Dropdown and Multiselection

Comment 1 Christophe Strobbe 2021-08-10 19:22:11 UTC

The bug report does not give a sufficiently convincing rationale for reducing the number of values that can be chosen from a drop-down list to just one value.

To make a comparison with HTML, the select element has always allowed developers to enable the selection of multiple values (by adding the attribute "multiple"): https://www.w3.org/TR/html52/sec-forms.html#elementdef-select 

Moreover, the ODF 1.3 specification (released in June 2021) does not express a limitation either. Subchapter "13.5.13 <form:listbox>" of Part 3 says:

The <form:listbox> element defines an input control that allows a user to select one or more items from a list. It is an alternative representation for a group of radio buttons.

(Note that the last sentence contradicts the first; if more than value can be selected, the listbox is an alternative representation of a "group" of check boxes.)

The more cogent argument would be that selecting more than one value from a single list box is not user friendly for most users and even more difficult for keyboard-only users.
See for example the Stack Overflow question "Many people don't know how to multi-select items in a HTML <select> control, so…?" https://stackoverflow.com/q/204075/6002174 (The answers can be ignored in the context of this bug.)

The usability of multiselect drop-downs is sufficiently bad to require instructions for users near the drop-down list.

Comment 2 Buovjaga 2021-08-10 20:04:23 UTC

(In reply to Christophe Strobbe from comment #1)
> The bug report does not give a sufficiently convincing rationale for
> reducing the number of values that can be chosen from a drop-down list to
> just one value.
> 
> To make a comparison with HTML, the select element has always allowed
> developers to enable the selection of multiple values (by adding the
> attribute "multiple"):
> https://www.w3.org/TR/html52/sec-forms.html#elementdef-select 

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/select#attr-multiple

"This Boolean attribute indicates that multiple options can be selected in the list. If it is not specified, then only one option can be selected at a time. When multiple is specified, most browsers will show a scrolling list box instead of a single line dropdown."

So the browser implementations are in line with the listbox & dropdown differences of LibreOffice's form elements.

(In reply to Christophe Strobbe from comment #1)
> Moreover, the ODF 1.3 specification (released in June 2021) does not express
> a limitation either. Subchapter "13.5.13 <form:listbox>" of Part 3 says:
> 
> The <form:listbox> element defines an input control that allows a user to
> select one or more items from a list. It is an alternative representation
> for a group of radio buttons.

Right, as said in bug 72932 comment 22, multiselection for listboxes works fine.