LGTM2 - we already discussed the chromeos namespace/Blink extension path
over in
https://groups.google.com/a/chromium.org/g/blink-api-owners-discuss/c/q_bRRc_RxBo?e=48417069.
I do think Alex has good feedback on how to improve the explainer (which
may be useful for future efforts that try to bring this to the
interoperable web).
On 7/15/26 8:08 p.m., Alex Russell wrote:
Hey Edman,
I think we should perhaps schedule a call. For context, IWAs were an
initiative that I started with Mike West and Penny McLachlan, so I'm
fully aware of the design constraints that can (and do) apply to them.
The /explicit /design goal of IWAs is to avoid OS-specific designs and
specs that cannot be plausibly interoperable. I don't understand this
design as something that can't be made interoperable, and if there's a
reason why, it would be good to see that called outsomewhere.
Regardless, I'm not sure that reads on the namespace or API shape, and
both remain problematic.
Marking this as "needs work" in chromestatus until we can confer.
Best,
Alex
On Wednesday, July 15, 2026 at 10:04:38 AM UTC-7 Reilly Grant wrote:
IWA OWNER LGTM
I would like to eventually see a version of this capability
available cross-platform. However as discussed with Blink API
OWNERS this ChromeOS-specific API is being proposed in a way that
avoids accidentally burning it into the platform and will need to
be redesigned if platform support is expanded.
Reilly Grant | Software Engineer |[email protected] |Google
Chrome <https://www.google.com/chrome>
On Wed, Jul 15, 2026 at 9:17 AM Chris Harrelson
<[email protected]> wrote:
LGTM1
This is a very specific API just on ChromeOS, and the global
variables are only visible to IWAs explicitly opted into it
via controls on that OS. It doesn't set a new precedent.
This also aligns with the plan of action discussed on
blink-api-owners-dsicuss.
On Mon, Jul 13, 2026 at 1:05 PM 'Edman Anjos' via blink-dev
<[email protected]> wrote:
Hi Alex, thanks a lot for your reply,
there's some additional context I can share about this
feature:
* This feature is designed as a ChromeOS-specific Blink
extension exclusively for Isolated Web Apps (IWAs). It is
not a general web standard or cross-platform web API, and
will not become one. Access is further restricted to
allowlisted applications. Because the target audience and
platform scope are so narrow, standardization is not a
goal in this feature.
* We first proposed this style of APIs on
blink-api-owners-discuss
<https://groups.google.com/a/chromium.org/g/blink-api-owners-discuss/c/q_bRRc_RxBo/m/iAaMUIbOAAAJ>.
`setShape` is our first (and currently only planned) API
following this proposal. The use of
`chromeos.isolatedWebApp.*` comes from the need of a
namespace that won't pollute standard web or IWA API
surfaces, or potentially other ChromeOS-only APIs.
* The API signature and behavior comes from the existing
`chrome.app.window.setShape` API for Chrome Apps on
ChromeOS. Partners are already familiar with the Chrome
App API, so mirroring it for the IWA API greatly
simplifies adoption.
I hope this clarifies things.
Thanks again,
Edman
On Monday, July 13, 2026 at 8:44:21 PM UTC+2 Alex Russell
wrote:
Hey folks,
I'm /very/ excited to see this capability coming to
the web!
At the same time, the shape of this proposal is not
going to pass muster in current form.
First, we can't be embedding the name `chromeos` into
APIs that can be used across platforms. We should hope
and expect for a day when IWAs are lit up more
broadly, so putting this in a CrOS-specific namespace
is a bad smell. It also isn't clear that this should
be prefixed with an IWA-specific namespace.
Second, it isn't clear that this making format is
common to other masking formats on the web. I don't
see a list of considered design alternatives for these
(and other) API shape concerns in the Explainer, which
in and of itself is concerning. Can you please reach
out to a current or former TAG memeber in your org to
get guidance on API shape?
Best,
Alex
On Wednesday, July 8, 2026 at 9:58:26 AM UTC-7
Chromestatus wrote:
*Contact emails*
[email protected], [email protected]
*Explainer*
https://github.com/explainers-by-googlers/chromeos-iwa-apis/blob/main/window-shape-explainer.md
<https://github.com/explainers-by-googlers/chromeos-iwa-apis/blob/main/window-shape-explainer.md>
*Specification*
https://explainers-by-googlers.github.io/chromeos-iwa-apis
<https://explainers-by-googlers.github.io/chromeos-iwa-apis>
*Design docs*
https://docs.google.com/document/d/1zPr1QgS-bXsJE7nrO44zx9RBopR4gHuvHxfcqxsX5Ag/edit?tab=t.0#heading=h.pcgro84kqnh3
<https://docs.google.com/document/d/1zPr1QgS-bXsJE7nrO44zx9RBopR4gHuvHxfcqxsX5Ag/edit?tab=t.0#heading=h.pcgro84kqnh3>
*Summary*
Window Shape API enables allowlisted [Isolated Web
Apps](https://chromeos.dev/en/web/isolated-web-apps
<https://chromeos.dev/en/web/isolated-web-apps>)
on ChromeOS to customize their window shape. By
enabling non-rectangular and non-contiguous window
layouts, developers can implement unique user
experiences (such as widgets, floating panels, and
overlays) that match the look-and-feel of native
applications. The API
`window.chromeos.isolatedWebApp.setShape` requires
the window to be in the unframed display mode and
requires the window-management permission to be
granted. Administrators can manage this feature
with existing policies for window management: -
[DefaultWindowManagementSetting](https://chromeenterprise.google/policies/#DefaultWindowManagementSetting
<https://chromeenterprise.google/policies/#DefaultWindowManagementSetting>)
configures the default state for the window
management for all apps. The policies below can
override this default. -
[WindowManagementAllowedForUrls](https://chromeenterprise.google/policies/#WindowManagementAllowedForUrls
<https://chromeenterprise.google/policies/#WindowManagementAllowedForUrls>)
allows IWAs with specified origins to enter
unframed mode and set custom window shapes without
any user interaction. -
[WindowManagementBlockedForUrls](https://chromeenterprise.google/policies/#WindowManagementBlockedForUrls
<https://chromeenterprise.google/policies/#WindowManagementBlockedForUrls>)
blocks the permission for specified origins,
forcing Chrome to remove any custom window shapes
and fallback to other available display modes.
*Blink component*
UI>Browser>WebAppInstalls>Isolated
<https://issues.chromium.org/issues?q=customfield1222907:%22UI%3EBrowser%3EWebAppInstalls%3EIsolated%22>
*Web Feature ID*
Missing feature
*Motivation*
/No information provided/
*Initial public proposal*
/No information provided/
*TAG review*
N/A - TAG review is not needed for IWA APIs
https://crsrc.org/c/docs/website/site/blink/launching-features/isolated-web-apps/index.md;l=73;drc=a5459539e0dfc093d8dc137fb9f8a72ddf5dcbb3
<https://crsrc.org/c/docs/website/site/blink/launching-features/isolated-web-apps/index.md;l=73;drc=a5459539e0dfc093d8dc137fb9f8a72ddf5dcbb3>
*TAG review status*
Not applicable
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
N/A, this feature is not meant to be implemented
by other browsers.
/Gecko/: No signal
/WebKit/: No signal
/Web developers/: No signals
/Other signals/:
*Ergonomics*
N/A
*Activation*
N/A, the feature is a single JS API that follows
the same behavior as a pre-existing Chrome App
API. Developers already know how to use it.
*Security*
See
https://github.com/explainers-by-googlers/chromeos-iwa-apis/blob/main/window-shape-explainer.md#security--privacy-considerations
<https://github.com/explainers-by-googlers/chromeos-iwa-apis/blob/main/window-shape-explainer.md#security--privacy-considerations>
In summary: The custom shape can be used to create
a hidden window, or for clickjacking. We mitigate
this by requiring a minimum shape size of 10x10
pixels, and by enforcing an allowlist of partners
that can use this API.
*WebView application risks*
Does this intent deprecate or change behavior of
existing APIs, such that it has potentially high
risk for Android WebView-based applications?
N/A
*Debuggability*
N/A
*Will this feature be supported on all six Blink
platforms (Windows, Mac, Linux, ChromeOS, Android,
and Android WebView)?*
No
This feature is implemented as a Blink extensions
for Chrome on ChromeOS. It will not be available
in any other platform.
*Is this feature fully tested by
web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
No
*Flag name on about://flags*
enable-chromeos-isolated-web-app-set-shape
*Finch feature name*
/No information provided/
*Non-finch justification*
/No information provided/
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Availability expectation*
Feature is available only in Chrome on ChromeOS,
and only for allowlisted IWAs.
*Adoption expectation*
Feature is used by allowlisted IWAs within 12
months of launch in Chrome.
*Adoption plan*
Work with partners: The feature is currently
available behind a feature flag in ChromeOS, and
two partners already use it to develop new IWAs.
The target release of their IWAs is 26Q4.
*Non-OSS dependencies*
Does the feature depend on any code or APIs
outside the Chromium open source repository and
its open-source dependencies to function?
N/A
*Estimated milestones*
Shipping on desktop 152
*Anticipated spec changes*
Open questions about a feature may be a source of
future web compat or interop issues. Please list
open issues (e.g. links to known github issues in
the project for the feature specification) whose
resolution may introduce web compat/interop risk
(e.g., changing to naming or structure of the API
in a non-backward-compatible way).
N/A
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5075144470036480?gate=6125215051546624
<https://chromestatus.com/feature/5075144470036480?gate=6125215051546624>
This intent message was generated by Chrome
Platform Status <https://chromestatus.com>.
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