Feature: Added an action to toggle dual pane mode

src/Files.App/Actions/Show/ToggleDualPaneAction.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Files Community
+// Licensed under the MIT License.
+
+namespace Files.App.Actions
+{
+	internal sealed partial class ToggleDualPaneAction : ObservableObject, IToggleAction
+	{
+		private readonly IContentPageContext ContentPageContext = Ioc.Default.GetRequiredService<IContentPageContext>();
+		private readonly IGeneralSettingsService generalSettingsService = Ioc.Default.GetRequiredService<IGeneralSettingsService>();
+
+		public string Label
+			=> Strings.ToggleDualPane.GetLocalizedResource();
+
+		public string Description
+			=> Strings.ToggleDualPaneDescription.GetLocalizedResource();
+
+		public bool IsOn
+			=> ContentPageContext.IsMultiPaneActive;
+
+		public ToggleDualPaneAction()
+		{
+			ContentPageContext.PropertyChanged += ContentPageContext_PropertyChanged;
+		}
+
+		public Task ExecuteAsync(object? parameter = null)
+		{
+			if (IsOn)
+				ContentPageContext.ShellPage?.PaneHolder.CloseOtherPane();
+			else
+				ContentPageContext.ShellPage?.PaneHolder.OpenSecondaryPane(arrangement: generalSettingsService.ShellPaneArrangementOption);
+
+			return Task.CompletedTask;
+		}
+
+		private void ContentPageContext_PropertyChanged(object? sender, PropertyChangedEventArgs e)
+		{
+			switch (e.PropertyName)
+			{
+				case nameof(IContentPageContext.ShellPage):
+				case nameof(IContentPageContext.IsMultiPaneActive):
+					OnPropertyChanged(nameof(IsOn));
+					break;
+			}
+		}
+	}
+}

src/Files.App/Data/Commands/Manager/CommandCodes.cs

@@ -28,6 +28,7 @@ public enum CommandCodes
 		ToggleToolbar,
 		ToggleShelfPane,
 		ToggleFilterHeader,
+		ToggleDualPane,
 
 		// File System
 		CopyItem,

src/Files.App/Data/Commands/Manager/CommandManager.cs

@@ -59,6 +59,7 @@ public IRichCommand this[HotKey hotKey]
 		public IRichCommand ToggleToolbar => commands[CommandCodes.ToggleToolbar];
 		public IRichCommand ToggleShelfPane => commands[CommandCodes.ToggleShelfPane];
 		public IRichCommand ToggleFilterHeader => commands[CommandCodes.ToggleFilterHeader];
+		public IRichCommand ToggleDualPane => commands[CommandCodes.ToggleDualPane];
 		public IRichCommand SelectAll => commands[CommandCodes.SelectAll];
 		public IRichCommand InvertSelection => commands[CommandCodes.InvertSelection];
 		public IRichCommand ClearSelection => commands[CommandCodes.ClearSelection];
@@ -266,6 +267,7 @@ public IEnumerator<IRichCommand> GetEnumerator() =>
 			[CommandCodes.ToggleToolbar] = new ToggleToolbarAction(),
 			[CommandCodes.ToggleShelfPane] = new ToggleShelfPaneAction(),
 			[CommandCodes.ToggleFilterHeader] = new ToggleFilterHeaderAction(),
+			[CommandCodes.ToggleDualPane] = new ToggleDualPaneAction(),
 			[CommandCodes.SelectAll] = new SelectAllAction(),
 			[CommandCodes.InvertSelection] = new InvertSelectionAction(),
 			[CommandCodes.ClearSelection] = new ClearSelectionAction(),

src/Files.App/Data/Commands/Manager/ICommandManager.cs

@@ -33,6 +33,7 @@ public interface ICommandManager : IEnumerable<IRichCommand>
 		IRichCommand ToggleToolbar { get; }
 		IRichCommand ToggleShelfPane { get; }
 		IRichCommand ToggleFilterHeader { get; }
+		IRichCommand ToggleDualPane { get; }
 
 		IRichCommand CopyItem { get; }
 		IRichCommand CopyItemPath { get; }

src/Files.App/Data/Contracts/IShellPanesPage.cs

@@ -54,6 +54,11 @@ public interface IShellPanesPage : IDisposable, INotifyPropertyChanged
 		/// </summary>
 		public void CloseActivePane();
 
+		/// <summary>
+		/// Closes the non active/focused pane.
+		/// </summary>
+		public void CloseOtherPane();
+
 		/// <summary>
 		/// Focuses the other pane.
 		/// </summary>

src/Files.App/Strings/en-US/Resources.resw

@@ -1106,6 +1106,12 @@
   <data name="ToggleFilterHeaderDescription" xml:space="preserve">
     <value>Toggle visibility of the filter header</value>
   </data>
+  <data name="ToggleDualPane" xml:space="preserve">
+    <value>Toggle dual pane</value>
+  </data>
+  <data name="ToggleDualPaneDescription" xml:space="preserve">
+    <value>Toggle dual pane mode</value>
+  </data>
   <data name="DetailsPanePreviewNotAvaliableText" xml:space="preserve">
     <value>No preview available</value>
   </data>

src/Files.App/Views/ShellPanesPage.xaml.cs

@@ -336,6 +336,18 @@ ShellPaneArrangement is ShellPaneArrangement.Vertical
 			}
 		}
 
+		/// <inheritdoc/>
+		public void CloseOtherPane()
+		{
+			if (!IsMultiPaneActive)
+				return;
+
+			if (ActivePane == (IShellPage)GetPane(0)!)
+				RemovePane(1);
+			else
+				RemovePane(0);
+		}
+
 		/// <inheritdoc/>
 		public void CloseActivePane()
 		{