feat: add intermediary window display states

GlazeWM.Domain/Common/Enums/DisplayState.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace GlazeWM.Domain.Common.Enums
+{
+  public enum DisplayState
+  {
+    Shown,
+    Showing,
+    Hidden,
+    Hiding,
+  }
+}

GlazeWM.Domain/Containers/CommandHandlers/RedrawContainersHandler.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Linq;
+using GlazeWM.Domain.Common.Enums;
 using GlazeWM.Domain.Containers.Commands;
 using GlazeWM.Domain.UserConfigs;
 using GlazeWM.Domain.Windows;
+using GlazeWM.Domain.Workspaces;
 using GlazeWM.Infrastructure.Bussing;
 using static GlazeWM.Infrastructure.WindowsApi.WindowsApiService;
 
@@ -71,14 +73,28 @@ private void SetWindowPosition(Window window)
         SetWindowPosFlags.FrameChanged |
         SetWindowPosFlags.NoActivate |
         SetWindowPosFlags.NoCopyBits |
-        SetWindowPosFlags.NoSendChanging;
+        SetWindowPosFlags.NoSendChanging |
+        SetWindowPosFlags.AsyncWindowPos;
+
+      var workspace = window.Ancestors.OfType<Workspace>().First();
+      var isWorkspaceDisplayed = workspace.IsDisplayed;
 
       // Show or hide the window depending on whether the workspace is displayed.
-      if (window.IsDisplayed)
+      if (isWorkspaceDisplayed)
         defaultFlags |= SetWindowPosFlags.ShowWindow;
       else
         defaultFlags |= SetWindowPosFlags.HideWindow;
 
+      // Transition display state depending on whether window will be shown/hidden.
+      window.DisplayState = window.DisplayState switch
+      {
+        DisplayState.Hidden or
+        DisplayState.Hiding when isWorkspaceDisplayed => DisplayState.Showing,
+        DisplayState.Shown or
+        DisplayState.Showing when !isWorkspaceDisplayed => DisplayState.Hiding,
+        _ => window.DisplayState
+      };
+
       if (window is TilingWindow)
       {
         SetWindowPos(

GlazeWM.Domain/Containers/Container.cs

@@ -150,7 +150,7 @@ public IEnumerable<Container> DescendantFocusOrder
 
     public bool IsDetached()
     {
-      return Parent is null;
+      return Parent is null || Index == -1;
     }
 
     public bool HasChildren()

GlazeWM.Domain/Windows/CommandHandlers/UnmanageWindowHandler.cs

@@ -42,10 +42,6 @@ public CommandResponse Handle(UnmanageWindowCommand command)
       if (focusTarget is null)
         return CommandResponse.Ok;
 
-      // The OS automatically switches focus to a different window after closing. If
-      // there are focusable windows, then set focus *after* the OS sets focus. This will
-      // cause focus to briefly flicker to the OS focus target and then to the WM's focus
-      // target.
       _bus.Invoke(new SetFocusedDescendantCommand(focusTarget));
       _containerService.HasPendingFocusSync = true;
       _windowService.UnmanagedOrMinimizedStopwatch.Restart();

GlazeWM.Domain/Windows/EventHandlers/WindowFocusedHandler.cs

@@ -1,9 +1,11 @@
 using System.Linq;
+using GlazeWM.Domain.Common.Enums;
 using GlazeWM.Domain.Common.Utils;
 using GlazeWM.Domain.Containers;
 using GlazeWM.Domain.Containers.Commands;
 using GlazeWM.Domain.Containers.Events;
 using GlazeWM.Domain.Workspaces;
+using GlazeWM.Domain.Workspaces.Commands;
 using GlazeWM.Infrastructure.Bussing;
 using GlazeWM.Infrastructure.Common.Events;
 using Microsoft.Extensions.Logging;
@@ -36,7 +38,8 @@ public void Handle(WindowFocusedEvent @event)
       var window = _windowService.GetWindows()
         .FirstOrDefault(window => window.Handle == @event.WindowHandle);
 
-      if (window is null || window?.IsDisplayed == false)
+      // Ignore event if window is unmanaged or being hidden by the WM.
+      if (window is null || window.DisplayState is DisplayState.Hiding)
         return;
 
       _logger.LogWindowEvent("Native focus event", window);
@@ -49,13 +52,33 @@ public void Handle(WindowFocusedEvent @event)
 
       var unmanagedStopwatch = _windowService.UnmanagedOrMinimizedStopwatch;
 
-      if (unmanagedStopwatch?.ElapsedMilliseconds < 100)
+      // Handle overriding focus on close/minimize. After a window is closed or minimized,
+      // the OS or the closed application might automatically switch focus to a different
+      // window. To force focus to go to the WM's target focus container, we reassign any
+      // focus events 100ms after close/minimize. This will cause focus to briefly flicker
+      // to the OS focus target and then to the WM's focus target.
+      if (unmanagedStopwatch.IsRunning && unmanagedStopwatch.ElapsedMilliseconds < 100)
       {
         _logger.LogDebug("Overriding native focus.");
         _bus.Invoke(new SyncNativeFocusCommand());
         return;
       }
 
+      // Handle focus events from windows on hidden workspaces. For example, if Discord
+      // is forcefully shown by the OS when it's on a hidden workspace, switch focus to
+      // Discord's workspace.
+      if (window.DisplayState is DisplayState.Hidden)
+      {
+        _logger.LogWindowEvent("Focusing off-screen window", window);
+
+        var workspace = WorkspaceService.GetWorkspaceFromChildContainer(window);
+        _bus.Invoke(new FocusWorkspaceCommand(workspace.Name));
+        _bus.Invoke(new SetFocusedDescendantCommand(window));
+        _bus.Invoke(new RedrawContainersCommand());
+        _bus.Emit(new FocusChangedEvent(window));
+        return;
+      }
+
       // Update the WM's focus state.
       _bus.Invoke(new SetFocusedDescendantCommand(window));
       _bus.Emit(new FocusChangedEvent(window));

GlazeWM.Domain/Windows/EventHandlers/WindowHiddenHandler.cs

@@ -1,4 +1,5 @@
 using System.Linq;
+using GlazeWM.Domain.Common.Enums;
 using GlazeWM.Domain.Common.Utils;
 using GlazeWM.Domain.Containers.Commands;
 using GlazeWM.Domain.Monitors.Commands;
@@ -39,18 +40,28 @@ public void Handle(WindowHiddenEvent @event)
       var window = _windowService.GetWindows()
         .FirstOrDefault(window => window.Handle == windowHandle);
 
-      // Ignore events where the window isn't managed or is actually supposed to be hidden. Since
-      // window events are processed in a sequence, also handle case where the window is not
-      // actually hidden anymore when the event is processed.
-      if (window?.IsDisplayed != true || WindowService.IsHandleVisible(window.Handle))
+      // Ignore event if window is unmanaged.
+      if (window is null)
         return;
 
       _logger.LogWindowEvent("Window hidden", window);
 
-      // Detach the hidden window from its parent.
-      _bus.Invoke(new UnmanageWindowCommand(window));
-      _bus.Invoke(new RedrawContainersCommand());
-      _bus.Invoke(new SyncNativeFocusCommand());
+      // Update the display state.
+      if (window.DisplayState is DisplayState.Hiding)
+      {
+        window.DisplayState = DisplayState.Hidden;
+        return;
+      }
+
+      // Unmanage the window if it's not in a display state transition. Also, since window
+      // events are not 100% guaranteed to be in correct order, we need to ignore events
+      // where the window is not actually hidden.
+      if (window.DisplayState is DisplayState.Shown && !WindowService.IsHandleVisible(window.Handle))
+      {
+        _bus.Invoke(new UnmanageWindowCommand(window));
+        _bus.Invoke(new RedrawContainersCommand());
+        _bus.Invoke(new SyncNativeFocusCommand());
+      }
     }
   }
 }

GlazeWM.Domain/Windows/EventHandlers/WindowShownHandler.cs

@@ -1,20 +1,28 @@
 using System.Linq;
+using GlazeWM.Domain.Common.Enums;
+using GlazeWM.Domain.Common.Utils;
 using GlazeWM.Domain.Containers.Commands;
 using GlazeWM.Domain.Monitors.Commands;
 using GlazeWM.Domain.Windows.Commands;
 using GlazeWM.Infrastructure.Bussing;
 using GlazeWM.Infrastructure.Common.Events;
+using Microsoft.Extensions.Logging;
 
 namespace GlazeWM.Domain.Windows.EventHandlers
 {
   internal sealed class WindowShownHandler : IEventHandler<WindowShownEvent>
   {
     private readonly Bus _bus;
+    private readonly ILogger<WindowShownHandler> _logger;
     private readonly WindowService _windowService;
 
-    public WindowShownHandler(Bus bus, WindowService windowService)
+    public WindowShownHandler(
+      Bus bus,
+      ILogger<WindowShownHandler> logger,
+      WindowService windowService)
     {
       _bus = bus;
+      _logger = logger;
       _windowService = windowService;
     }
 
@@ -32,13 +40,21 @@ public void Handle(WindowShownEvent @event)
       var window = _windowService.GetWindows()
         .FirstOrDefault(window => window.Handle == windowHandle);
 
-      // Ignore cases where window is already managed.
-      if (window is not null || !WindowService.IsHandleManageable(windowHandle))
+      // Manage the window if it's manageable.
+      if (window is null && WindowService.IsHandleManageable(windowHandle))
+      {
+        _bus.Invoke(new ManageWindowCommand(windowHandle));
+        _bus.Invoke(new RedrawContainersCommand());
+        _bus.Invoke(new SyncNativeFocusCommand());
         return;
+      }
+
+      if (window is not null)
+        _logger.LogWindowEvent("Showing window", window);
 
-      _bus.Invoke(new ManageWindowCommand(@event.WindowHandle));
-      _bus.Invoke(new RedrawContainersCommand());
-      _bus.Invoke(new SyncNativeFocusCommand());
+      // Update display state if window is already managed.
+      if (window?.DisplayState == DisplayState.Showing)
+        window.DisplayState = DisplayState.Shown;
     }
   }
 }

GlazeWM.Domain/Windows/Window.cs

@@ -1,7 +1,8 @@
 using System;
+using System.Diagnostics;
 using GlazeWM.Domain.Common;
+using GlazeWM.Domain.Common.Enums;
 using GlazeWM.Domain.Containers;
-using GlazeWM.Domain.Workspaces;
 using GlazeWM.Infrastructure.WindowsApi;
 using static GlazeWM.Infrastructure.WindowsApi.WindowsApiService;
 
@@ -14,6 +15,11 @@ public abstract class Window : Container
 
     public IntPtr Handle { get; }
 
+    /// <summary>
+    /// Whether window is shown, hidden, or in an intermediary state.
+    /// </summary>
+    public DisplayState DisplayState { get; set; } = DisplayState.Shown;
+
     /// <summary>
     /// The placement of the window when floating. Initialized with window's placement on launch
     /// and updated on resize/move whilst floating.
@@ -39,11 +45,6 @@ protected Window(IntPtr handle, Rect floatingPlacement, RectDelta borderDelta)
       BorderDelta = borderDelta;
     }
 
-    /// <summary>
-    /// Windows are displayed if their parent workspace is displayed.
-    /// </summary>
-    public bool IsDisplayed => WorkspaceService.GetWorkspaceFromChildContainer(this).IsDisplayed;
-
     public string ProcessName =>
       WindowService.GetProcessOfHandle(Handle)?.ProcessName ?? string.Empty;
 

GlazeWM.Domain/Workspaces/CommandHandlers/FocusWorkspaceHandler.cs

@@ -59,9 +59,10 @@ public CommandResponse Handle(FocusWorkspaceCommand command)
       // Save currently focused workspace as recent for command "recent"
       _workspaceService.MostRecentWorkspace = focusedWorkspace;
 
+      _logger.LogDebug("WorkspaceToFocus: {WorkspaceToFocusName}", workspaceToFocus.Name);
+
       // Set focus to the last focused window in workspace. If the workspace has no descendant
       // windows, then set focus to the workspace itself.
-      _logger.LogDebug("WorkspaceToFocus: {WorkspaceToFocusName}", workspaceToFocus.Name);
       var containerToFocus = workspaceToFocus.HasChildren()
         ? workspaceToFocus.LastFocusedDescendant
         : workspaceToFocus;
@@ -70,11 +71,8 @@ public CommandResponse Handle(FocusWorkspaceCommand command)
       _containerService.HasPendingFocusSync = true;
 
       // Display the workspace to switch focus to.
-      if (focusedWorkspace.Parent == workspaceToFocus.Parent)
-      {
-        _containerService.ContainersToRedraw.Add(displayedWorkspace);
-        _containerService.ContainersToRedraw.Add(workspaceToFocus);
-      }
+      _containerService.ContainersToRedraw.Add(displayedWorkspace);
+      _containerService.ContainersToRedraw.Add(workspaceToFocus);
 
       // Get empty workspace to destroy (if any are found). Cannot destroy empty workspaces if
       // they're the only workspace on the monitor or are pending focus.

GlazeWM.Domain/Workspaces/CommandHandlers/MoveWindowToWorkspaceHandler.cs

@@ -54,11 +54,19 @@ public CommandResponse Handle(MoveWindowToWorkspaceCommand command)
 
       var focusTarget = WindowService.GetFocusTargetAfterRemoval(windowToMove);
 
+      // Since the workspace that gets displayed is the last focused child, focus needs to be
+      // reassigned to the displayed workspace.
+      var targetMonitor = targetWorkspace.Parent as Monitor;
+      var focusResetTarget = targetWorkspace.IsDisplayed ? null : targetMonitor.LastFocusedDescendant;
+
       if (windowToMove is TilingWindow)
         MoveTilingWindowToWorkspace(windowToMove as TilingWindow, targetWorkspace);
       else
         _bus.Invoke(new MoveContainerWithinTreeCommand(windowToMove, targetWorkspace, false));
 
+      if (focusResetTarget is not null)
+        _bus.Invoke(new SetFocusedDescendantCommand(focusResetTarget));
+
       // Reassign focus to descendant within the current workspace. Need to call
       // `SetFocusedDescendantCommand` for when commands like `FocusWorkspaceCommand` are called
       // immediately afterwards and they should behave as if `focusTarget` is the focused