1117253 - [e10s] Repaint web page jerky when open/close sidebar

Status: NEW

(Core :: Layout, defect, P3)

Description

[Alice0775 White]

Steps to reproduce:
1. Open web page
   e.g. https://developer.mozilla.org/en-US/docs/Mercurial_FAQ
2. Toggle sidebar (Crtl+B) and repeat
3. Compare with non-e10s window

Actual Results:
  On e10s window: 
    Repaint web page jerky
    Vertical scroll bar jumps/flickers

Expected Results:
  Content should repaint smoothly, it should be like on non-e10s window.

Comment 1

[Alice0775 White]

not a recent regression, but this happens only on e10s window

Comment 2

[Alice0775 White]

Attachment: screencast

Comment 3

[Jim Mathies [:jimm]]

resizing content is still pretty crummy, I see empty space to the right of content briefly before content repaints. This only happen when closing the sidebar.

Comment 5

[John Gruen [:jgruen]]

We're seeing this in the Notes experiment as well.

Comment 6

[Albert Scheiner [:alberts]]

Attachment: bug-1117253_repaint_sidebar.ogv

Was wondering if this could get higher priority now that the sidebar got a bit more love during Photon development (bug 1353421)? Also uploading another screencast as the original one is rendering green for me for some reason.

Comment 8

[Cristina Badescu [:cbadescu], Experiments QA]

Attachment: Resizing browser issue.mp4

While testing on latest Nightly build (58.0a1, Build ID: 20171004100049), I've observed something similar when resizing the window. I've tried to find a regression window, but I got as far as Nightly 50.0 and it was still reproducing.

Seems that this issue is reproducible only when "Enable multi-process Nightly" option is checked. Managed to reproduce it on Win 10 x64, 7x64 and mac OS 10.12. Moreover, the issue is reproducible on Windows 7 x32 even when "Enable multi-process Nightly" option is not checked.

Attached a screen recording of the issue.
Should we file a new bug for this? Or it's the same root cause and we can consider this one to cover this behavior too?

Also, since they seem to have similar behaviors, and the sidebar got some attention in Photon as Albert mentioned in comment 5, I'm gonna move the issue to a better component to get a second opinion on it.

Comment 9

[roxleitan]

Attachment: Screencast 2017-10-06 01:41:30.mp4

Mozilla/5.0 (X11; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20171005220204

Similar behaviour when resizing the window on Ubuntu 16.04 x64. 
The issue is reproducible also with 'Enable multi-process Nightly" option disabled.

Should I log a new bug for this?