Moving a window to another screen unexpectedly changes its size

[Shijie-Hotone]

Bug Description

When moving an existing window to another screen using Loop's screen-switching actions, the window's size changes unexpectedly.

This appears to happen because Loop preserves the window frame as a percentage of the current screen's usable bounds, then applies that percentage to the destination screen. On displays with different resolutions, scaling, visible frame sizes, menu bar / Dock availability, or padding, this changes the actual window size in points.

Steps To Reproduce

1. Use a Mac with multiple displays whose usable screen frames differ.
2. Put a normal resizable window on one display.
3. Trigger a Loop screen-switching action such as Next Screen, Previous Screen, Top Screen, or Bottom Screen.
4. Observe the window after it moves to the destination display.

Expected Behavior

Moving a window to another screen should preserve the window's current size in points. The position can be remapped or clamped to fit the destination screen, but the width and height should not be recalculated from the destination screen's dimensions.

Actual Behavior

The window is moved to the destination screen, but its width and/or height changes. For example, moving from a larger usable screen area to a smaller one makes the window smaller; moving in the opposite direction makes it larger.

Technical Notes

I checked Loop 1.4.2 and the current develop branch. The behavior seems to come from the screen-switching path in LoopManager.swift.

When newAction.direction.willChangeScreen is true and the current action is .noSelection or manipulates an existing frame, Loop computes:

let proportionalSize = CGRect(
    x: (currentFrame.minX - adjustedBounds.minX) / adjustedBounds.width,
    y: (currentFrame.minY - adjustedBounds.minY) / adjustedBounds.height,
    width: currentFrame.width / adjustedBounds.width,
    height: currentFrame.height / adjustedBounds.height
)

Then it creates an autogenerated custom action with:

unit: .percentage,
width: proportionalSize.width * 100,
height: proportionalSize.height * 100,
xPoint: proportionalSize.minX * 100,
yPoint: proportionalSize.minY * 100,
positionMode: .coordinates,
sizeMode: .custom

Later, custom percentage actions are resolved against the destination screen bounds, so the size changes when the destination bounds differ.

A possible fix would be to preserve currentFrame.width and currentFrame.height in points for screen-switching actions, map the origin or center to the destination screen, and only clamp the final origin to keep the window on-screen.

macOS Version

macOS 26.5.1 (25F80)

Loop Version

1.4.2 (1693)

Additional Context

This is specifically about moving the same window to another display. It is not about focus-only actions such as Focus Left, Focus Right, or Focus Next in Stack.

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 can help with testing a fix

[mrkai77]

Hey @Shijie-Hotone, this is actually intended behavior! That said, you’re welcome to implement a non-user-facing UserDefaults flag to disable this resizing, so windows are never resized when moving across different screens. Let me know :)