184025 - Selection of more items than fit in the view of a multiple selection box causes the box to scroll unexpectedly

Status: NEW

(Core :: Layout: Form Controls, defect, P4)

Description

[Loren Williams]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021130
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021130

When you shift-click to select a list of items in a mulitple selection box on a
form and the first item is no longer visible, in addition to highlighting the
items, Mozilla re-orients the selection box to place the last item selected at
the bottom of the box.  This process works in reverse as well - if you
shift-click an item above the first one selected, the multiple selection box is
re-oriented upwards.  Users, however, do not expect this change and may find it
disorienting.

Reproducible: Always

Steps to Reproduce:
Click on any item in the Product window.  Scroll down until the highlighted item
is completely out of view.  Then shift-click an item in the middle of the
multiple selection window and watch the window re-orient itself.
Actual Results:  
The multiple selection window moved the contents inside, which I was not expecting.

Expected Results:  
Mozilla should only have highlighted the items I selected.  Adjusting the view
of the multiple selection box as well makes it harder to confirm that one did
select what one intended to select.

Comment 1

[Boris Zbarsky [:bzbarsky]]

This is probably a result of bug 143815, in which ScrollFrameIntoView was fixed
to handle nested scroll views....

I'm surprised that SCROLL_IF_NOT_VISIBLE is moving things that much, though...

Comment 2

[[e-mail]]

Actually this has a simple explanation. Bug 34297 introduced code that scrolled the index into view whenever an option was selected. Thus a multiple selection scrolls all the intervening indices into view. Finally the clicked index is scrolled into view but by then the damage has been done.