1187990 - Scroll amount is very small with keyboard if Zoom level is > 100%

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

[Alice0775 White]

[Tracking Requested - why for this release]:

Steps to reproduce
1. Open web page
   (e.g. http://ftp.mozilla.org/pub/mozilla.org/firefox/tinderbox-builds/mozilla-inbound-win64-pgo/ )
2. Zoom in several times (Ctrl++)
3. Open the same page in new tab
4. Keypress End (or Down Arrow)
   --- Bug! Scroll amound is small

extra step
5. Keypress End to scroll bottom
   --- scrolls as expected
6. Middle click reload button to duplicate tab
7. Keypress Home (or Up Arrow)
   --- Bug! Scroll amound is small

Actual Results:
Scroll amount is very small with keyboard if Zoom level is > 100%
The bug happens only at the first attempt in a new tab

Disabled APZ fixes the problem.

Expected Results:
Scroll amount is normal



Regression window(force enable APZ)
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=fa5d3f420ee6&tochange=60f82e40f039

Regressed by:
60f82e40f039	George Wright — Bug 1157941 - If the current PresShell is suppressed, paint the old one if it is available r=tn,Enn

Comment 1

[Jim Mathies [:jimm]]

I was able to reproduce this: the shorter scroll only happens the first time you hit End. A subsequent key entry will scroll the page to the bottom. Entering Home and then End again scrolls to top then bottom of the page correctly. So it seems we miscalculate the distance to the bottom of the page the first time we scroll via a End, but after that everything works.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

It's probably worth checking to see if the patch on bug 1187792 fixes this. It fixed some related-sounding issues.

Comment 3

[Gary [:streetwolf52]]

Text zoom does not have this problem, only page zoom.

Comment 4

[Gary [:streetwolf52]]

Things appear to be working OK now.  I'm on inbound and have bug 1187792 applied.  Perhaps that did fix the problem as mentioned in Comment 2.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Marking as fixed by bug 1187792 as per comment 4. If anybody can still reproduce this issue, please reopen.