View Full Version : [OPEN] Dropdown combos cause vertical scrollbar flash in Firefox

J.C. Bize
4 Jun 2007, 5:00 PM

Apologies if this has already been reported, I did search the forums :)

If Firefox, clicking on the dropdown arrow causes the vertical scrollbar to "flash" very briefly. I can reproduce this on the "Form and Combobox" samples, as well as in the "Toolbar and Menus" sample. IE7 works fine.

Note that this only happens the first time the dropdown arrow is clicked... on subsequent dropdown arrow clicks, the problem does not occur.

Here is a screenshot of the exact moment when this happens... boy did I have fun timing that screen capture. ;)


11 Jul 2007, 3:32 AM
In the past few releases 1.1b1, b2, rc1 I've too noticed that when a combo box is first expanded, there's a "flash" where a browser vertical scroll bar appears for a brief moment before disappearing. This only happens on FF and only happens the first time a combobox is expanded. It occurs with all apdaters.

To reproduce, go to the 'Tools and Menu' example in the documentation center using FF. Now click on the 'state' comboc box field drop down. You'll notice the above mentioned flash when this is doen the first time. The flas is more noticeable for larger combo boxes and those with remote data.


J.C. Bize
2 Aug 2007, 10:23 AM
just wanted to mention this is still an issue in the final v1.1 using Firefox


3 Aug 2007, 2:18 PM
Could these bugs be related? Please see my post here (http://extjs.com/forum/showthread.php?t=10444).

Does the scrollbar still flash when you have a large number of items in the combobox? In my experience the scrollbar appears on page load because of all the blank space that gets added at the bottom of the page, and it stays like that until you click to open the combo. When you do, the blank space at the bottom of the page disappears, causing the scrollbar to shrink to normal, or disappear (if the page was not supposed to scroll in the first place). This quick change in the scrollbar when clicking the dropdown arrow could also be described as a scrollbar "flash".

This behavior becomes very obvious when you really push the combo and display, say, 1000 items.



3 Aug 2007, 5:48 PM
The flash is from dynamically determining the size (height) of the list. If anyone has a suggestion of a workaround, we would be happy to try it out.

4 Aug 2007, 8:00 AM
I've seen this flashing artifact too.

This might be naive, but what about this idea?

Render the list offscreen in negative X territority. To prevent the scrollbar from appearing briefly, render it in a container with a fixed vertical size with scrolling enabled. After render, grab the size then move the node in the DOM where it should have gone in the first place.

J.C. Bize
13 Sep 2007, 8:15 AM
Just thought I'd mention this is no longer an issue in the ExtJS 2.0 dev samples that were posted last week.