2062398 - Single window tiled/snapped to the right of the screen does not get the "tiled" attribute in Windows 11

Status: NEW

(Core :: Widget: Win32, defect, P3)

Description

[Sam Foster [:sfoster] (he/him)]

Attachment: tiled-window-snapped-right.png

STR:

• Open a single Nightly window in Windows 11
• Drag it to the lower right of the screen until the outline of the 50% right-aligned snapping area shows, and drop it there
• Confirm window is full height and 50% width, with the window edge flush to the screen edge
• In the browser toolbox, check if the documentElement has the "tiled" attribute

ER:

• document.documentElement.hasAttribute("tiled") returns true

AR:

• document.documentElement.hasAttribute("tiled") returns false

See bug 2059533 for other screenshots and configurations which did work as expected.

Comment 1

[Sam Foster [:sfoster] (he/him)]

Follow-up from bug 2059533. See also bug 2062351 - the priority for this is a bit up in the air right now.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

I guess if/when this becomes useful on windows I can take a look.

Comment 3

[Stephen Thompson [:sthompson]]

On Windows 11 Home 25H2 26200.8875, I see the tiled attr set and unset in all of the scenarios I'd expect. I registered a MutationObserver on the documentElement to report to the console when the value changes.

Times when I see it set:

1. Win+left/right arrows (left/right 50% snap)
2. Win+up arrow twice (top 50% snap on the second up arrow, after passing through maximized state)
3. Mouse dragging to the window edges (left, right 50% snaps; top-left, top-right, bottom-left, bottom-right quarter-screen snaps; top-middleish positions to snap the left, middle, or right 1/3 of the screen)
4. Mouse dragging to the Snap Assist box and dropping on any specific position

I can't reproduce the issue from comment 0. The lower-right of the screen wants to do a 1/4 snap for me. I wonder if you are on an older build of Windows 11 and the snapping behavior is different... but IsWindowArranged should in theory be reporting snapped windows since Windows 10 version 1903/May 2019 Update.