Added a pre-process hook to InputManager,

And some documentation.

src/Perspex.Controls/TopLevel.cs

@@ -392,7 +392,7 @@ namespace Perspex.Controls
         /// <param name="e">The event args.</param>
         private void HandleInput(RawInputEventArgs e)
         {
-            _inputManager.Process(e);
+            _inputManager.ProcessInput(e);
         }
 
         /// <summary>

src/Perspex.Diagnostics/DevTools.xaml.cs

@@ -26,7 +26,7 @@ namespace Perspex.Diagnostics
             Root = root;
             DataContext = new DevToolsViewModel(root);
 
-            _keySubscription = InputManager.Instance.RawEventReceived
+            _keySubscription = InputManager.Instance.Process
                 .OfType<RawKeyEventArgs>()
                 .Subscribe(RawKeyDown);
         }

src/Perspex.Input/IInputManager.cs

@@ -3,16 +3,36 @@
 
 using System;
 using Perspex.Input.Raw;
-using Perspex.Layout;
 
 namespace Perspex.Input
 {
+    /// <summary>
+    /// Recieves input from the windowing subsystem and dispatches it to interested parties
+    /// for processing.
+    /// </summary>
     public interface IInputManager
     {
-        IObservable<RawInputEventArgs> RawEventReceived { get; }
+        /// <summary>
+        /// Gets an observable that notifies on each input event recieved before
+        /// <see cref="Process"/>.
+        /// </summary>
+        IObservable<RawInputEventArgs> PreProcess { get; }
 
+        /// <summary>
+        /// Gets an observable that notifies on each input event recieved.
+        /// </summary>
+        IObservable<RawInputEventArgs> Process { get; }
+
+        /// <summary>
+        /// Gets an observable that notifies on each input event recieved after
+        /// <see cref="Process"/>.
+        /// </summary>
         IObservable<RawInputEventArgs> PostProcess { get; }
 
-        void Process(RawInputEventArgs e);
+        /// <summary>
+        /// Processes a raw input event.
+        /// </summary>
+        /// <param name="e">The raw input event.</param>
+        void ProcessInput(RawInputEventArgs e);
     }
 }

src/Perspex.Input/InputManager.cs

@@ -2,28 +2,39 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Reactive.Subjects;
 using Perspex.Input.Raw;
 
 namespace Perspex.Input
 {
+    /// <summary>
+    /// Recieves input from the windowing subsystem and dispatches it to interested parties
+    /// for processing.
+    /// </summary>
     public class InputManager : IInputManager
     {
-        private readonly Subject<RawInputEventArgs> _rawEventReceived = new Subject<RawInputEventArgs>();
-
+        private readonly Subject<RawInputEventArgs> _preProcess = new Subject<RawInputEventArgs>();
+        private readonly Subject<RawInputEventArgs> _process = new Subject<RawInputEventArgs>();
         private readonly Subject<RawInputEventArgs> _postProcess = new Subject<RawInputEventArgs>();
 
+        /// <summary>
+        /// Gets the global instance of the input manager.
+        /// </summary>
         public static IInputManager Instance => PerspexLocator.Current.GetService<IInputManager>();
 
-        public IObservable<RawInputEventArgs> RawEventReceived => _rawEventReceived;
+        /// <inheritdoc/>
+        public IObservable<RawInputEventArgs> PreProcess => _preProcess;
+
+        /// <inheritdoc/>
+        public IObservable<RawInputEventArgs> Process => _process;
 
+        /// <inheritdoc/>
         public IObservable<RawInputEventArgs> PostProcess => _postProcess;
 
-        public void Process(RawInputEventArgs e)
+        /// <inheritdoc/>
+        public void ProcessInput(RawInputEventArgs e)
         {
-            _rawEventReceived.OnNext(e);
+            _process.OnNext(e);
             _postProcess.OnNext(e);
         }
     }

src/Perspex.Input/KeyboardDevice.cs

@@ -18,9 +18,9 @@ namespace Perspex.Input
 
         public KeyboardDevice()
         {
-            InputManager.RawEventReceived
+            InputManager.Process
                 .OfType<RawInputEventArgs>()
-                .Where(x => x.Device == this)
+                .Where(e => e.Device == this && !e.Handled)
                 .Subscribe(ProcessRawEvent);
         }
 

src/Perspex.Input/MouseDevice.cs

@@ -27,9 +27,9 @@ namespace Perspex.Input
         /// </summary>
         public MouseDevice()
         {
-            InputManager.RawEventReceived
+            InputManager.Process
                 .OfType<RawMouseEventArgs>()
-                .Where(x => x.Device == this)
+                .Where(e => e.Device == this && !e.Handled)
                 .Subscribe(ProcessRawEvent);
         }
 

tests/Perspex.Controls.UnitTests/TopLevelTests.cs

@@ -251,7 +251,7 @@ namespace Perspex.Controls.UnitTests
                     Key.A, InputModifiers.None);
                 impl.Object.Input(input);
 
-                inputManagerMock.Verify(x => x.Process(input));
+                inputManagerMock.Verify(x => x.ProcessInput(input));
             }
         }