don't pass focus when window is moved and followed to a different desktop (issue 116)

src/lib/layout/Column.ts

@@ -289,7 +289,7 @@ class Column {
         } else {
             this.resizeWindows();
             if (passFocus && windowToFocus !== null) {
-                windowToFocus.focus();
+                this.grid.focusPasser.request(windowToFocus);
             }
         }
 

src/lib/layout/Desktop.ts

@@ -14,13 +14,14 @@ class Desktop {
         private readonly config: Desktop.Config,
         private readonly getScreen: () => Output,
         layoutConfig: LayoutConfig,
+        focusPasser: FocusPassing.Passer,
     ) {
         this.scrollX = 0;
         this.gestureScrollXInitial = null;
         this.dirty = true;
         this.dirtyScroll = true;
         this.dirtyPins = true;
-        this.grid = new Grid(this, layoutConfig);
+        this.grid = new Grid(this, layoutConfig, focusPasser);
         this.clientArea = Desktop.getClientArea(this.getScreen(), kwinDesktop);
         this.tilingArea = Desktop.getTilingArea(this.clientArea, kwinDesktop, pinManager, config);
     }

src/lib/layout/Grid.ts

@@ -1,15 +1,17 @@
 class Grid {
     public readonly desktop: Desktop;
     public readonly config: LayoutConfig;
+    public readonly focusPasser: FocusPassing.Passer;
     private readonly columns: LinkedList<Column>;
     private lastFocusedColumn: Column|null;
     private width: number;
     private userResize: boolean; // is any part of the grid being resized by the user
     private readonly userResizeFinishedDelayer: Delayer;
 
-    constructor(desktop: Desktop, config: LayoutConfig) {
+    constructor(desktop: Desktop, config: LayoutConfig, focusPasser: FocusPassing.Passer) {
         this.desktop = desktop;
         this.config = config;
+        this.focusPasser = focusPasser;
         this.columns = new LinkedList();
         this.lastFocusedColumn = null;
         this.width = 0;
@@ -169,7 +171,7 @@ class Grid {
 
         this.desktop.onLayoutChanged();
         if (passFocus && columnToFocus !== null) {
-            columnToFocus.focus();
+            this.focusPasser.request(columnToFocus);
         } else {
             this.desktop.autoAdjustScroll();
         }

src/lib/workspace.ts

@@ -1,4 +1,4 @@
-function initWorkspaceSignalHandlers(world: World) {
+function initWorkspaceSignalHandlers(world: World, focusPasser: FocusPassing.Passer) {
     const manager = new SignalManager();
 
     manager.connect(Workspace.windowAdded, (kwinClient: KwinClient) => {
@@ -15,11 +15,13 @@ function initWorkspaceSignalHandlers(world: World) {
 
     manager.connect(Workspace.windowActivated, (kwinClient: KwinClient|null) => {
         if (kwinClient === null) {
-            return;
+            focusPasser.activate();
+        } else {
+            focusPasser.clear();
+            world.do((clientManager, desktopManager) => {
+                clientManager.onClientFocused(kwinClient);
+            });
         }
-        world.do((clientManager, desktopManager) => {
-            clientManager.onClientFocused(kwinClient);
-        });
     });
 
     manager.connect(Workspace.currentDesktopChanged, () => {

src/lib/world/DesktopManager.ts

@@ -7,7 +7,8 @@ class DesktopManager {
     constructor(
         private readonly pinManager: PinManager,
         private readonly config: Desktop.Config,
-        public readonly layoutConfig: LayoutConfig,
+        private readonly layoutConfig: LayoutConfig,
+        private readonly focusPasser: FocusPassing.Passer,
         currentActivity: string,
         currentDesktop: KwinDesktop,
     ) {
@@ -54,6 +55,7 @@ class DesktopManager {
             this.config,
             () => this.selectedScreen,
             this.layoutConfig,
+            this.focusPasser,
         );
         this.desktops.set(desktopKey, desktop);
         return desktop;

src/lib/world/FocusPassing.ts

@@ -0,0 +1,44 @@
+namespace FocusPassing {
+    export class Passer {
+        private currentRequest: Request | null = null;
+
+        public request(target: Focuser) {
+            this.currentRequest = new Request(target, Date.now());
+        }
+
+        public clear() {
+            this.currentRequest = null;
+        }
+
+        public activate() {
+            if (this.currentRequest === null) {
+                return;
+            }
+
+            if (this.currentRequest.isExpired()) {
+                this.clear();
+                return;
+            }
+
+            this.currentRequest.target.focus();
+            this.clear();
+        }
+    }
+
+    class Request {
+        private static readonly validMs = 200;
+
+        constructor(
+            public readonly target: Focuser,
+            private readonly time: number,
+        ) {}
+
+        public isExpired() {
+            return Date.now() - this.time > Request.validMs;
+        }
+    }
+
+    interface Focuser {
+        focus(): void;
+    }
+}

src/lib/world/World.ts

@@ -8,7 +8,8 @@ class World {
     private readonly cursorFollowsFocus: boolean;
 
     constructor(config: Config) {
-        this.workspaceSignalManager = initWorkspaceSignalHandlers(this);
+        const focusPasser = new FocusPassing.Passer();
+        this.workspaceSignalManager = initWorkspaceSignalHandlers(this, focusPasser);
         this.cursorFollowsFocus = config.cursorFollowsFocus;
 
         let presetWidths = {
@@ -68,6 +69,7 @@ class World {
                 gestureScrollStep: config.gestureScrollStep,
             },
             layoutConfig,
+            focusPasser,
             Workspace.currentActivity,
             Workspace.currentDesktop,
         );