🐞 Window snapping fully broken after updating to developer version

[AlejandroVolkova]

Bug Description

I was using the stable version of Loop and just updated to the developer version. One of the changes has completely broken the window snapping functionality. When dragging with three fingers on the trackpad, only the animation is shown, but the window does not move. Sometimes it even freezes, as if something is adding lag. it feels very strange. However, when using shortcuts, Loop works as expected.

Affected Scope

Performance

Steps to Reproduce

1. Open any application window.
2. On the trackpad, drag the window using three fingers to trigger window snapping.
3. Observe that only the snapping animation is shown, but the window does not move.
4. In some cases, the window freezes or lags, as if something is blocking the action.

Reproducibility

Always

Expected vs Actual Behavior

Self explanatory

Screen Recordings / Screenshots

WS_Fully_Broken.mp4

Severity

Critical (major functionality broken)

macOS Version

macOS 26.2

Loop Version

Version 🧪 1.4.1 (1683)

Did You Try the Development Build?

Yes

Additional Context

No response

Final Checks

• My issue is written in English.
• My issue title is descriptive.
• This is a single bug (multiple bugs should be reported individually).
• I have looked to see if this is a duplicate of another bug report.
• I can help with further investigation.
• I can help with developing a fix for this issue.

[manuthebyte]

Maybe this has something to do with #1011, I will check.

[mrkai77]

Fix is now included in the latest development build :)

[AlejandroVolkova]

I tested the applied fix and although the initial issue seems to have been addressed, the snapping feature still performs poorly. Previously, the behavior was smooth, but now when dragging windows there are temporary freezes that prevent normal use.

For example, when using Safari, I used to be able to move windows quickly, but now they freeze for a few seconds. In addition, the animation can show graphical glitches. The overall experience is unreliable and far from the fluid performance it had before.

[mrkai77]

Thanks for letting me know! I have a PR (#1015) that reworks much of how previews work, as well as how actions (e.g. window movement) are executed, so I expect it will resolve this. I’ll update this thread once it’s merged! (re-opening so I don’t forget)

[AlejandroVolkova]

@mrkai77 Thanks for the update! I’ll keep an eye out and will test the developer version once it’s available :). For now, I’ll stay on the stable release because I was literally fighting with windows 😅.

Window.Freeze.Snap.Issues.mp4

[manuthebyte]

@mrkai77 I think I would possibly have a fix for this behaviour, should I work through and open a pr, or wait for your changes first to be merged?

[SenpaiHunters]

Hey, @manuthebyte I'll respond in Kai's stead, as he's asleep. You can open a PR without needing to wait for any pushes by cloning the branch git clone --branch concurrency-and-improvements https://github.com/mrkai77/loop for any fixes or changes in your PR.

[manuthebyte]

Good one, I will check if maybe the bug doesn't even occur on the concurrency branch. Ty :)

[mrkai77]

Hey! I made some further optimizations to WindowDragManager, and things should be fixed now. I did notice a bug when the system window manager is enabled, though, where it causes behavior similar to what you showed in the video. My guess is that when macOS moves windows, it temporarily disables dragging so users can’t interfere with the movement. Unfortunately, that’s outside of Loop’s control, but you should see smooth behavior again in window snapping if you disable the system window manager!