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Bug 334755

Summary:	[Combo] Selected item not visible in the list if it was scrolled before
Product:	[RT] RAP	Reporter:	Ivan Furnadjiev <ivan>
Component:	RWT	Assignee:	Project Inbox <rap-inbox>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	P3	CC:	tbuschto
Version:	1.4
Target Milestone:	1.4 M7
Hardware:	All
OS:	All
Whiteboard:

Description Ivan Furnadjiev

2011-01-19 06:00:39 EST

Reproducible with Controls Demo:
1. Start Controls Demo -> Button Tab
2. Open Cursor combo drop-down list and scroll it, to make the "null" selection not visible anymore
3. Click somewhere else to close the drop-down list.
4. Open the drop-list again - scroll offset is on the old position and the selected item is not visible.
With the new Scrollbar implementation the ListItem#scrollIntoView() is not working anymore.

Comment 1 Tim Buschtoens

2011-03-23 12:45:14 EDT

The scrollIntoView call is actually working, its more an issue of the order in which it is called:

- list.setDisplay( true ) is called in Combo.js
- flush
- in Combo the lists appear event causes the scrollIntoView call
- scrollIntoView works like expected, but the resulting dom-scroll-event is not fired until the javascript thread is free again.
- Next in Scrollable#_onClientAppear "_syncClientArea" is called, which 
sets the clientArea (the actual list) back to the (unchanged) scroll-position stored in the ScrollBar.
- After all that the dom-scroll-event is finally fired, triggering Scrollable#_onscroll, which then in turn calls "_syncClientArea", trying to store the new scroll position in the scrollbar, which should have happend before it got reset.

So basically, the problem is a combination of the fact that dom-events dont get fired while javascript is processed and that Combo gets the appear event before the list itself does.

Comment 2 Tim Buschtoens

2011-03-23 12:49:30 EDT

Correction: the second "_syncClientArea" should actually be "_syncScrollBars"

Comment 3 Tim Buschtoens

2011-03-23 13:00:23 EDT

Fixed in CVS HEAD by calling "_syncScrollBars" explicitly after "scrollIntoView".