Well it works, just pretty ugly looking.

osu.Game.Tests/Visual/Settings/TestSceneKeyBindingPanel.cs

@@ -4,6 +4,7 @@
 using System.Diagnostics;
 using System.Linq;
 using NUnit.Framework;
+using osu.Framework.Input.Bindings;
 using osu.Framework.Testing;
 using osu.Framework.Threading;
 using osu.Game.Overlays;
@@ -31,13 +32,16 @@ namespace osu.Game.Tests.Visual.Settings
         [Test]
         public void TestClickTwiceOnClearButton()
         {
+            SettingsKeyBindingRow firstSettingRow = null;
             KeyBindingRow firstRow = null;
 
             AddStep("click first row", () =>
             {
-                firstRow = panel.ChildrenOfType<KeyBindingRow>().First();
+                firstSettingRow = panel.ChildrenOfType<SettingsKeyBindingRow>().First();
-                InputManager.MoveMouseTo(firstRow);
+                InputManager.MoveMouseTo(firstSettingRow);
                 InputManager.Click(MouseButton.Left);
+
+                firstRow = firstSettingRow.KeyBindingRow;
             });
 
             AddStep("schedule button clicks", () =>
@@ -71,7 +75,7 @@ namespace osu.Game.Tests.Visual.Settings
 
             AddStep("click first row with two bindings", () =>
             {
-                multiBindingRow = panel.ChildrenOfType<KeyBindingRow>().First(row => row.Defaults.Count() > 1);
+                multiBindingRow = panel.ChildrenOfType<SettingsKeyBindingRow>().First(row => row.KeyBindingRow.Defaults.Count() > 1).KeyBindingRow;
                 InputManager.MoveMouseTo(multiBindingRow);
                 InputManager.Click(MouseButton.Left);
             });
@@ -105,38 +109,67 @@ namespace osu.Game.Tests.Visual.Settings
         }
 
         [Test]
-        public void TestResetButtonOnBindings()
+        public void TestSingleBindResetButton()
         {
+            SettingsKeyBindingRow multiSettingsBindingRow = null;
             KeyBindingRow multiBindingRow = null;
 
             AddStep("click first row with two bindings", () =>
             {
+                multiSettingsBindingRow = panel.ChildrenOfType<SettingsKeyBindingRow>().First(row => row.KeyBindingRow.Defaults.Count() > 1);
                 multiBindingRow = panel.ChildrenOfType<KeyBindingRow>().First(row => row.Defaults.Count() > 1);
                 InputManager.MoveMouseTo(multiBindingRow);
                 InputManager.Click(MouseButton.Left);
+                InputManager.PressKey(Key.P);
+                InputManager.ReleaseKey(Key.P);
             });
 
+            AddUntilStep("restore button shown", () => multiSettingsBindingRow.ChildrenOfType<RestoreDefaultValueButton<bool>>().First().Alpha > 0);
+
             clickSingleBindResetButton();
 
             AddAssert("first binding cleared", () => multiBindingRow.ChildrenOfType<KeyBindingRow.KeyButton>().ElementAt(0).KeyBinding.KeyCombination.Equals(multiBindingRow.Defaults.ElementAt(0)));
-
-            AddStep("click second binding", () =>
-            {
-                var target = multiBindingRow.ChildrenOfType<KeyBindingRow.KeyButton>().ElementAt(1);
-
-                InputManager.MoveMouseTo(target);
-                InputManager.Click(MouseButton.Left);
-            });
-
-            clickSingleBindResetButton();
-
             AddAssert("second binding cleared", () => multiBindingRow.ChildrenOfType<KeyBindingRow.KeyButton>().ElementAt(1).KeyBinding.KeyCombination.Equals(multiBindingRow.Defaults.ElementAt(1)));
 
+            AddUntilStep("restore button hidden", () => multiSettingsBindingRow.ChildrenOfType<RestoreDefaultValueButton<bool>>().First().Alpha == 0);
+
             void clickSingleBindResetButton()
             {
-                AddStep("click reset button for single binding", () =>
+                AddStep("click reset button for bindings", () =>
                 {
-                    var clearButton = multiBindingRow.ChildrenOfType<KeyBindingRow.SingleBindResetButton>().Single();
+                    var clearButton = multiSettingsBindingRow.ChildrenOfType<RestoreDefaultValueButton<bool>>().Single();
+
+                    InputManager.MoveMouseTo(clearButton);
+                    InputManager.Click(MouseButton.Left);
+                });
+            }
+        }
+
+        [Test]
+        public void TestResetAllBindingsButton()
+        {
+            SettingsKeyBindingRow multiSettingsBindingRow = null;
+            KeyBindingRow multiBindingRow = null;
+
+            AddStep("click first row and press p", () =>
+            {
+                multiSettingsBindingRow = panel.ChildrenOfType<SettingsKeyBindingRow>().First(row => row.KeyBindingRow.Defaults.Count() > 1);
+                multiBindingRow = panel.ChildrenOfType<KeyBindingRow>().First();
+                InputManager.MoveMouseTo(multiBindingRow);
+                InputManager.Click(MouseButton.Left);
+                InputManager.PressKey(Key.P);
+                InputManager.ReleaseKey(Key.P);
+            });
+
+            clickResetAllBindingsButton();
+
+            AddAssert("bindings cleared", () => multiBindingRow.ChildrenOfType<KeyBindingRow.KeyButton>().ElementAt(0).KeyBinding.KeyCombination.Equals(multiBindingRow.Defaults.ElementAt(0)));
+
+            void clickResetAllBindingsButton()
+            {
+                AddStep("click reset button for all bindings", () =>
+                {
+                    var clearButton = panel.ChildrenOfType<ResetButton>().First();
 
                     InputManager.MoveMouseTo(clearButton);
                     InputManager.Click(MouseButton.Left);
@@ -176,4 +209,4 @@ namespace osu.Game.Tests.Visual.Settings
             AddAssert("first binding selected", () => multiBindingRow.ChildrenOfType<KeyBindingRow.KeyButton>().First().IsBinding);
         }
     }
-}
+}

osu.Game.Tests/Visual/Settings/TestSceneSettingsItem.cs

@@ -7,6 +7,7 @@ using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Testing;
 using osu.Game.Overlays.Settings;
+using osu.Game.Overlays;
 
 namespace osu.Game.Tests.Visual.Settings
 {
@@ -37,7 +38,7 @@ namespace osu.Game.Tests.Visual.Settings
 
         private class TestSettingsTextBox : SettingsTextBox
         {
-            public new Drawable RestoreDefaultValueButton => this.ChildrenOfType<RestoreDefaultValueButton>().Single();
+            public Drawable RestoreDefaultValueButton => this.ChildrenOfType<RestoreDefaultValueButton<string>>().Single();
         }
     }
-}
+}

osu.Game/Overlays/KeyBinding/KeyBindingRow.cs

@@ -4,12 +4,14 @@
 using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Extensions;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Effects;
 using osu.Framework.Graphics.Shapes;
+using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
 using osu.Game.Graphics;
@@ -22,7 +24,7 @@ using osuTK.Input;
 
 namespace osu.Game.Overlays.KeyBinding
 {
-    public class KeyBindingRow : Container, IFilterable
+    public class KeyBindingRow : Container, IFilterable, IHasCurrentValue<bool>
     {
         private readonly object action;
         private readonly IEnumerable<Framework.Input.Bindings.KeyBinding> bindings;
@@ -51,6 +53,13 @@ namespace osu.Game.Overlays.KeyBinding
         private FillFlowContainer cancelAndClearButtons;
         private FillFlowContainer<KeyButton> buttons;
 
+        private BindableWithCurrent<bool> isKeysDefaultValue;
+        public Bindable<bool> Current
+        {
+            get => isKeysDefaultValue.Current;
+            set => isKeysDefaultValue.Current = value;
+        }
+
         public IEnumerable<string> FilterTerms => bindings.Select(b => b.KeyCombination.ReadableString()).Prepend(text.Text.ToString());
 
         public KeyBindingRow(object action, IEnumerable<Framework.Input.Bindings.KeyBinding> bindings)
@@ -58,6 +67,11 @@ namespace osu.Game.Overlays.KeyBinding
             this.action = action;
             this.bindings = bindings;
 
+            isKeysDefaultValue = new BindableWithCurrent<bool>()
+            {
+                Default = true
+            };
+
             RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
 
@@ -71,6 +85,17 @@ namespace osu.Game.Overlays.KeyBinding
         [BackgroundDependencyLoader]
         private void load(OsuColour colours)
         {
+
+            isKeysDefaultValue.Value = bindings.Select(b => b.KeyCombination).SequenceEqual(Defaults);
+            isKeysDefaultValue.BindValueChanged(resetButtons =>
+            {
+                if (resetButtons.NewValue != resetButtons.OldValue && resetButtons.NewValue && !bindings.Select(b => b.KeyCombination).SequenceEqual(Defaults))
+                {
+                    RestoreDefaults();
+                    finalise();
+                }
+            });
+
             EdgeEffect = new EdgeEffectParameters
             {
                 Radius = 2,
@@ -109,7 +134,6 @@ namespace osu.Game.Overlays.KeyBinding
                     Children = new Drawable[]
                     {
                         new CancelButton { Action = finalise },
-                        new SingleBindResetButton { Action = singleBindReset },
                         new ClearButton { Action = clear },
                     },
                 }
@@ -129,6 +153,8 @@ namespace osu.Game.Overlays.KeyBinding
                 button.UpdateKeyCombination(d);
                 store.Update(button.KeyBinding);
             }
+
+            isKeysDefaultValue.Value = true;
         }
 
         protected override bool OnHover(HoverEvent e)
@@ -282,21 +308,29 @@ namespace osu.Game.Overlays.KeyBinding
             finalise();
         }
 
-        private void singleBindReset()
-        {
-            if (bindTarget == null)
-                return;
-
-            bindTarget.UpdateKeyCombination(Defaults.ElementAt(buttons.IndexOf(bindTarget)));
-            finalise();
-        }
-
         private void finalise()
         {
             if (bindTarget != null)
             {
                 store.Update(bindTarget.KeyBinding);
 
+                KeyCombination keyDefault = Defaults.ElementAt(buttons.IndexOf(bindTarget));
+                if (isKeysDefaultValue.Value)
+                {
+                    if (!keyDefault.Equals(bindTarget.KeyBinding.KeyCombination))
+                    {
+                        isKeysDefaultValue.Value = false;
+                    }
+                }
+                else
+                {
+                    if (keyDefault.Equals(bindTarget.KeyBinding.KeyCombination) &&
+                        buttons.Select(b => b.KeyBinding.KeyCombination).SequenceEqual(Defaults))
+                    {
+                        isKeysDefaultValue.Value = true;
+                    }
+                }
+
                 bindTarget.IsBinding = false;
                 Schedule(() =>
                 {
@@ -349,24 +383,6 @@ namespace osu.Game.Overlays.KeyBinding
             }
         }
 
-        public class SingleBindResetButton : TriangleButton
-        {
-            public SingleBindResetButton()
-            {
-                Text = "Reset";
-                Size = new Vector2(80, 20);
-            }
-
-            [BackgroundDependencyLoader]
-            private void load(OsuColour colours)
-            {
-                BackgroundColour = colours.Green;
-
-                Triangles.ColourDark = colours.GreenDark;
-                Triangles.ColourLight = colours.GreenLight;
-            }
-        }
-
         public class ClearButton : TriangleButton
         {
             public ClearButton()
@@ -487,4 +503,4 @@ namespace osu.Game.Overlays.KeyBinding
             }
         }
     }
-}
+}

osu.Game/Overlays/KeyBinding/KeyBindingsSubsection.cs

@@ -1,17 +1,20 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Input;
 using osu.Game.Overlays.Settings;
 using osu.Game.Rulesets;
 using osuTK;
 using osu.Game.Graphics;
+using osu.Framework.Input.Bindings;
 
 namespace osu.Game.Overlays.KeyBinding
 {
@@ -41,16 +44,12 @@ namespace osu.Game.Overlays.KeyBinding
                 int intKey = (int)defaultGroup.Key;
 
                 // one row per valid action.
-                Add(new KeyBindingRow(defaultGroup.Key, bindings.Where(b => ((int)b.Action).Equals(intKey)))
+                Add(new SettingsKeyBindingRow(defaultGroup, bindings, Ruleset));
-                {
-                    AllowMainMouseButtons = Ruleset != null,
-                    Defaults = defaultGroup.Select(d => d.KeyCombination)
-                });
             }
 
             Add(new ResetButton
             {
-                Action = () => Children.OfType<KeyBindingRow>().ForEach(k => k.RestoreDefaults())
+                Action = () => Children.OfType<SettingsKeyBindingRow>().ForEach(k => k.KeyBindingRow.RestoreDefaults())
             });
         }
     }
@@ -72,4 +71,4 @@ namespace osu.Game.Overlays.KeyBinding
             Triangles.ColourLight = colours.Pink;
         }
     }
-}
+}

osu.Game/Overlays/KeyBinding/SettingsKeyBindingRow.cs

@@ -0,0 +1,70 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.Linq;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets;
+
+namespace osu.Game.Overlays.KeyBinding
+{
+    public class SettingsKeyBindingRow : Container, IFilterable
+    {
+        private readonly IGrouping<object, Framework.Input.Bindings.KeyBinding> defaultGroup;
+        private readonly IEnumerable<Framework.Input.Bindings.KeyBinding> bindings;
+        public readonly KeyBindingRow KeyBindingRow;
+
+        private bool matchingFilter;
+
+        public bool MatchingFilter
+        {
+            get => matchingFilter;
+            set
+            {
+                matchingFilter = value;
+                this.FadeTo(!matchingFilter ? 0 : 1);
+            }
+        }
+
+        public bool FilteringActive { get; set; }
+
+        public IEnumerable<string> FilterTerms => bindings.Select(b => b.KeyCombination.ReadableString()).Prepend(defaultGroup.Key.ToString());
+
+        public SettingsKeyBindingRow(
+            IGrouping<object, Framework.Input.Bindings.KeyBinding> defaultGroup,
+            IEnumerable<Framework.Input.Bindings.KeyBinding> bindings,
+            RulesetInfo ruleset)
+        {
+            this.defaultGroup = defaultGroup;
+            this.bindings = bindings;
+
+            KeyBindingRow = new KeyBindingRow(defaultGroup.Key, bindings.Where(b => ((int)b.Action).Equals((int)defaultGroup.Key)))
+            {
+                AllowMainMouseButtons = ruleset != null,
+                Defaults = defaultGroup.Select(d => d.KeyCombination)
+            };
+
+
+            RestoreDefaultValueButton<bool> restoreDefaultButton;
+
+            RelativeSizeAxes = Axes.X;
+            AutoSizeAxes = Axes.Y;
+            Padding = new MarginPadding { Right = SettingsPanel.CONTENT_MARGINS };
+
+            InternalChildren = new Drawable[]
+            {
+                restoreDefaultButton = new RestoreDefaultValueButton<bool>(),
+                new FillFlowContainer
+                {
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
+                    Padding = new MarginPadding { Left = SettingsPanel.CONTENT_MARGINS },
+                    Child = KeyBindingRow
+                },
+            };
+
+            restoreDefaultButton.Bindable = KeyBindingRow.Current;
+        }
+    }
+}

osu.Game/Overlays/RestoreDefaultValueButton.cs

@@ -0,0 +1,119 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osuTK.Graphics;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Cursor;
+using osu.Framework.Graphics.Effects;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input.Events;
+using osu.Game.Graphics;
+using osuTK;
+
+namespace osu.Game.Overlays
+{
+    public class RestoreDefaultValueButton<T> : Container, IHasTooltip
+    {
+        public override bool IsPresent => base.IsPresent || Scheduler.HasPendingTasks;
+
+        private Bindable<T> bindable;
+
+        public Bindable<T> Bindable
+        {
+            get => bindable;
+            set
+            {
+                bindable = value;
+                bindable.ValueChanged += _ => UpdateState();
+                bindable.DisabledChanged += _ => UpdateState();
+                bindable.DefaultChanged += _ => UpdateState();
+                UpdateState();
+            }
+        }
+
+        private Color4 buttonColour;
+
+        private bool hovering;
+
+        public RestoreDefaultValueButton()
+        {
+            RelativeSizeAxes = Axes.Y;
+            Width = SettingsPanel.CONTENT_MARGINS;
+            Alpha = 0f;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colour)
+        {
+            buttonColour = colour.Yellow;
+
+            Child = new Container
+            {
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                RelativeSizeAxes = Axes.Both,
+                CornerRadius = 3,
+                Masking = true,
+                Colour = buttonColour,
+                EdgeEffect = new EdgeEffectParameters
+                {
+                    Colour = buttonColour.Opacity(0.1f),
+                    Type = EdgeEffectType.Glow,
+                    Radius = 2,
+                },
+                Size = new Vector2(0.33f, 0.8f),
+                Child = new Box { RelativeSizeAxes = Axes.Both },
+            };
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            UpdateState();
+        }
+
+        public string TooltipText => "revert to default";
+
+        protected override bool OnClick(ClickEvent e)
+        {
+            if (bindable != null && !bindable.Disabled)
+                bindable.SetDefault();
+            return true;
+        }
+
+        protected override bool OnHover(HoverEvent e)
+        {
+            hovering = true;
+            UpdateState();
+            return false;
+        }
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            hovering = false;
+            UpdateState();
+        }
+
+        public void SetButtonColour(Color4 buttonColour)
+        {
+            this.buttonColour = buttonColour;
+            UpdateState();
+        }
+
+        public void UpdateState() => Scheduler.AddOnce(updateState);
+
+        private void updateState()
+        {
+            if (bindable == null)
+                return;
+
+            this.FadeTo(bindable.IsDefault ? 0f :
+                hovering && !bindable.Disabled ? 1f : 0.65f, 200, Easing.OutQuint);
+            this.FadeColour(bindable.Disabled ? Color4.Gray : buttonColour, 200, Easing.OutQuint);
+        }
+    }
+}

osu.Game/Overlays/Settings/SettingsItem.cs

@@ -108,7 +108,8 @@ namespace osu.Game.Overlays.Settings
 
         protected SettingsItem()
         {
-            RestoreDefaultValueButton restoreDefaultButton;
+
+            RestoreDefaultValueButton<T> restoreDefaultButton;
 
             RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
@@ -116,7 +117,7 @@ namespace osu.Game.Overlays.Settings
 
             InternalChildren = new Drawable[]
             {
-                restoreDefaultButton = new RestoreDefaultValueButton(),
+                restoreDefaultButton = new RestoreDefaultValueButton<T>(),
                 FlowContent = new FillFlowContainer
                 {
                     RelativeSizeAxes = Axes.X,
@@ -146,101 +147,5 @@ namespace osu.Game.Overlays.Settings
             if (labelText != null)
                 labelText.Alpha = controlWithCurrent.Current.Disabled ? 0.3f : 1;
         }
-
-        protected internal class RestoreDefaultValueButton : Container, IHasTooltip
-        {
-            public override bool IsPresent => base.IsPresent || Scheduler.HasPendingTasks;
-
-            private Bindable<T> bindable;
-
-            public Bindable<T> Bindable
-            {
-                get => bindable;
-                set
-                {
-                    bindable = value;
-                    bindable.ValueChanged += _ => UpdateState();
-                    bindable.DisabledChanged += _ => UpdateState();
-                    bindable.DefaultChanged += _ => UpdateState();
-                    UpdateState();
-                }
-            }
-
-            private Color4 buttonColour;
-
-            private bool hovering;
-
-            public RestoreDefaultValueButton()
-            {
-                RelativeSizeAxes = Axes.Y;
-                Width = SettingsPanel.CONTENT_MARGINS;
-                Padding = new MarginPadding { Vertical = 1.5f };
-                Alpha = 0f;
-            }
-
-            [BackgroundDependencyLoader]
-            private void load(OsuColour colour)
-            {
-                buttonColour = colour.Yellow;
-
-                Child = new Container
-                {
-                    Anchor = Anchor.Centre,
-                    Origin = Anchor.Centre,
-                    RelativeSizeAxes = Axes.Both,
-                    CornerRadius = 3,
-                    Masking = true,
-                    Colour = buttonColour,
-                    EdgeEffect = new EdgeEffectParameters
-                    {
-                        Colour = buttonColour.Opacity(0.1f),
-                        Type = EdgeEffectType.Glow,
-                        Radius = 2,
-                    },
-                    Width = 0.33f,
-                    Child = new Box { RelativeSizeAxes = Axes.Both },
-                };
-            }
-
-            protected override void LoadComplete()
-            {
-                base.LoadComplete();
-                UpdateState();
-            }
-
-            public string TooltipText => "revert to default";
-
-            protected override bool OnClick(ClickEvent e)
-            {
-                if (bindable != null && !bindable.Disabled)
-                    bindable.SetDefault();
-                return true;
-            }
-
-            protected override bool OnHover(HoverEvent e)
-            {
-                hovering = true;
-                UpdateState();
-                return false;
-            }
-
-            protected override void OnHoverLost(HoverLostEvent e)
-            {
-                hovering = false;
-                UpdateState();
-            }
-
-            public void UpdateState() => Scheduler.AddOnce(updateState);
-
-            private void updateState()
-            {
-                if (bindable == null)
-                    return;
-
-                this.FadeTo(bindable.IsDefault ? 0f :
-                    hovering && !bindable.Disabled ? 1f : 0.65f, 200, Easing.OutQuint);
-                this.FadeColour(bindable.Disabled ? Color4.Gray : buttonColour, 200, Easing.OutQuint);
-            }
-        }
     }
-}
+}