fix: add SSMenuAgent (Screen Sharing) to immovable items

[coygeek]

Summary

macOS prevents the SSMenuAgent menu extra (binoculars / Screen Sharing icon) from being repositioned via Command+drag. The item visually follows the cursor during the drag but springs back to its original position on mouse-up. This causes Thaw to retry the move 8 times and then show an error dialog.

• Add SSMenuAgent (com.apple.SSMenuAgent:Item-0) to immovableItems so the layout editor disables dragging for this item entirely
• Add .ssMenuAgent namespace constant and tag constant following the existing pattern
• Add .ssMenuAgent to isSystemItem for consistent system item identity

Investigation Details

Environment

• macOS 26.3 (Tahoe), MacBook Pro, Thaw signed release
• SSMenuAgent tag: com.apple.SSMenuAgent:Item-0 (sourcePID correctly resolved via XPC)

Manual Command+drag test

Holding Command and dragging the binoculars icon in the menu bar: the icon follows the cursor during the drag, but when released, it springs back to its original position. This matches the behavior of Clock and Control Center (both already in immovableItems).

Layout editor drag

Dragging SSMenuAgent from the Visible bar to the Hidden bar in Thaw Settings → Menu Bar Layout produces this error dialog:

"SSMenuAgent" took too long to respond
Please try again. If the error persists, please file a bug report.

This is EventError.itemResponseTimeout — the move() function posts Command+drag events, waitForMoveEventResponse() polls for position change, the item never moves, and after 8 retry attempts the error propagates.

Diagnostic logs (from log stream --predicate 'subsystem == "com.stonerl.Thaw"')

cacheItemsRegardless: item tag=com.apple.SSMenuAgent:Item-0 (windowID: 15030) title=Item-0 windowID=15030 sourcePID=44321 ownerPID=450

The XPC service correctly resolves the true owner PID (44321 = SSMenuAgent), while ownerPID reports 450 (Control Center) due to the macOS 26 CGWindowList regression (FB18327911).

Code path

1. LayoutBarPaddingView.move() → appState.itemManager.move(item:to:)
2. move() passes item.isMovable check (SSMenuAgent not in immovableItems)
3. postMoveEvents() creates Command+mouseDown/mouseUp CGEvents targeted at SSMenuAgent's sourcePID
4. waitForMoveEventResponse() polls item origin for ~100ms — item never moves
5. Throws EventError.itemResponseTimeout → caught by retry loop
6. After 8 attempts, error propagates → NSAlert shown

Context

This issue also exists in Ice (the upstream project Thaw was forked from). I originally discovered and reported it there as jordanbaird/Ice#885, where it manifests as a "Missing bounds rectangle" error instead. Now that I'm using Thaw, I'm submitting the fix here since Thaw is the actively maintained fork. The root cause is the same: macOS prevents SSMenuAgent from being repositioned, but neither Ice nor Thaw had it in their immovable items list.

Test plan

• Verify SSMenuAgent (binoculars) icon is grayed out / not draggable in the Menu Bar Layout editor
• Verify no error dialog appears when the layout is loaded with SSMenuAgent present
• Verify other items (Stats, 1Password, etc.) remain fully draggable
• Verify Clock and Control Center remain immovable (no regression)

Related: jordanbaird/Ice#885

🤖 Generated with Claude Code

[stonerl]

LGTM, thank you very much for your contribution.