Open Bug 1653491 Opened 4 years ago Updated 4 years ago

Items from the navigation bar shift back and forth by ~1px when dragging an item to the toolbar in customize mode while having layout.css.devPixelsPerPx pref set to 1.5

Categories

(Firefox :: Toolbars and Customization, defect, P5)

Desktop
All
defect

Tracking

()

People

(Reporter: atrif, Unassigned)

Details

(Keywords: regression)

Attachments

(1 file)

Attached image customize_devPixels.gif

Affected versions

  • 80.0a1 (20200716212737)
  • 79.0b9 (20200717001501)
  • 78.0.2 (20200708170202)

Affected platforms

  • Ubuntu 18.04
  • macOS 10.14
  • Windows 10x64

Steps to reproduce

  1. Open Firefox and set layout.css.devPixelsPerPx to 1.5.
  2. Enter Customize and drag any item to the toolbar.

Expected result

  • No glitches presented.

Actual result

  • Right side elements are shaking.

Regression range
Reproducible with 74.0a1(20200202214642). I Will search for one ASAP.

Notes

  • Attached a screen recording.
    Severity S4
Has Regression Range: --- → no
Has STR: --- → yes
Summary: Items from the navigation bar are shaking when adding and item while having layout.css.devPixelsPerPx pref set to 1.5 → Items from the navigation bar are shaking when adding an item while having layout.css.devPixelsPerPx pref set to 1.5

Attaching the regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=1b4c59eef820b46eb0037aca68f83a15088db45f&tochange=ab2d700fda2b4934d24227216972dce9fac19b74

Note that on older builds the issue is very intermittent and the regression range may not be accurate.

Has Regression Range: no → yes

This is basically some kind of rounding error in the maths of the placeholder space that we create for the item. It's probably hard to reproduce reliably and/or fix reliably across all resolutions, as it'll depend on the exact pixel and device pixel offsets of all the different elements, the size of the (variable size) flex items like the address bar and the flexible spaces, etc. It's also very subtle. Doesn't seem worth tracking on a per-release basis.

Severity: -- → S4
Priority: -- → P5
Summary: Items from the navigation bar are shaking when adding an item while having layout.css.devPixelsPerPx pref set to 1.5 → Items from the navigation bar shift back and forth by ~1px when dragging an item to the toolbar in customize mode while having layout.css.devPixelsPerPx pref set to 1.5
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