Fix on-window-detected floating rule causing brief tiling flash

[willzeng274]

Fixes two related visual glitches when an on-window-detected rule applies layout floating:

1. The new window briefly flashes at its tiled position before floating.
2. Sibling tiling windows briefly shift to make room for the incoming window's tile slot.

See the commit message for root cause and fix details.

Related discussion: #2016

Summary:

• if you set an app as layout floating in [on-window-detected], sometimes it tries to tile it first

---

• I've read CONTRIBUTING.md
• My PR contains atomic commits (each commit is a self-contained change with a descriptive message explaining what and why)
• My PR doesn't contain merge commits (I've rebased on top of the target branch instead)
• If my PR is ready for review, I've marked it as such (not a draft)
• I've added a link to the relevant GitHub Discussion (if applicable)
• I've tested my changes manually

[nikitabobko]

I didn't manage to reproduce the bug. But I believe that it could be theoretically happening.

I am not sure that I like the idea of introducing an additional boolean flag. This flickering is not the only problem that is caused by sessions interleaving (ref: #1311)

Question: does the following patch fix the issue?

Details

diff --git a/Sources/AppBundle/layout/layoutRecursive.swift b/Sources/AppBundle/layout/layoutRecursive.swift
index bc005b9b..f718a735 100644
--- a/Sources/AppBundle/layout/layoutRecursive.swift
+++ b/Sources/AppBundle/layout/layoutRecursive.swift
@@ -4,6 +4,7 @@ extension Workspace {
     @MainActor
     func layoutWorkspace() async throws {
         if isEffectivelyEmpty { return }
+        try checkCancellation()
         let rect = workspaceMonitor.visibleRectPaddedByOuterGaps
         // If monitors are aligned vertically and the monitor below has smaller width, then macOS may not allow the
         // window on the upper monitor to take full width. rect.height - 1 resolves this problem
@@ -15,6 +16,7 @@ extension Workspace {
 extension TreeNode {
     @MainActor
     fileprivate func layoutRecursive(_ point: CGPoint, width: CGFloat, height: CGFloat, virtual: Rect, _ context: LayoutContext) async throws {
+        try checkCancellation()
         let physicalRect = Rect(topLeftX: point.x, topLeftY: point.y, width: width, height: height)
         switch nodeCases {
             case .workspace(let workspace):
@@ -68,6 +70,7 @@ private struct LayoutContext {
 extension Window {
     @MainActor
     fileprivate func layoutFloatingWindow(_ context: LayoutContext) async throws {
+        try checkCancellation()
         let workspace = context.workspace
         let windowRect = try await getAxRect() // Probably not idempotent
         let currentMonitor = windowRect?.center.monitorApproximation
@@ -95,6 +98,7 @@ extension Window {
 
     @MainActor
     fileprivate func layoutFullscreen(_ context: LayoutContext) {
+        try checkCancellation()
         let monitorRect = noOuterGapsInFullscreen
             ? context.workspace.workspaceMonitor.visibleRect
             : context.workspace.workspaceMonitor.visibleRectPaddedByOuterGaps
@@ -105,6 +109,7 @@ extension Window {
 extension TilingContainer {
     @MainActor
     fileprivate func layoutTiles(_ point: CGPoint, width: CGFloat, height: CGFloat, virtual: Rect, _ context: LayoutContext) async throws {
+        try checkCancellation()
         var point = point
         var virtualPoint = virtual.topLeftCorner
 
@@ -140,6 +145,7 @@ extension TilingContainer {
 
     @MainActor
     fileprivate func layoutAccordion(_ point: CGPoint, width: CGFloat, height: CGFloat, virtual: Rect, _ context: LayoutContext) async throws {
+        try checkCancellation()
         guard let mruIndex: Int = mostRecentChild?.ownIndex else { return }
         for (index, child) in children.enumerated() {
             let padding = CGFloat(config.accordionPadding)

[willzeng274]

hmm... for some reason I can't reproduce the issue anymore either, not sure what caused it tbh, I will report if I encounter the bug again.