Twenty Fifteen flattering with Twitterfeed

[derElch]

This is a follow-up to #29987.

i created here a GIF Animation which shows the trouble.
if i'm using the official Twitter Feed (included by Twitter JS Code or Jetpack Plugin doesn't make a difference) it begins to falter while scrolling down.

pls see:

Problem can be comprehended at rideSonic.ch
(WordPress 4.1, Jetpack 3.3, TwentyFifteen 1.0)

Theme is only modified in small parts but the bug exists in the main theme too. Bug discovered in Firefox 34.0.05 and IE 11.0.96, in Google Chrome it works as it should (mostly). Is this a real bug or just something which the browser (FF/IE) can't handle?

an "other" bug:
if scrolling down, it stops above the page bottom. after scrolling forward/downward it beginns to flatter. this happens mostly after visiting a page with less content (not so large pages) and/or if i beginn immediately after page loading to scroll.

pls see:

Thank you very much and have a nice day.

[lancewillett]

Can anyone else repeat, please? Please note your OS version and browser version -- using "default" WP install with unmodified Twenty Fifteen theme, if possible.

[jartes]

In 31734.diff moved the calculation of the sidebar height to the scroll() function to calculate the sidebar height every time we scroll. Now, this is calculated in the beginning, when the dynamic widgets with iframes, like Twitter, are not rendered yet.

[jartes]

As the reporter said the error was visible only in FF and IE. I was able to reproduce the error in FF 36.0.4 (Mac) with my local install at the 31912 trunk revision: ​https://cloudup.com/cu2ghhv1dSv.

[lancewillett]

In 31934:

Twenty Fifteen: adjust scroll behavior to make sure sidebar height is calculated during scroll events, not just resize events.

Fixes #31734. Props jartes, lancewillett.