Fix "Deselect all" mods button becoming enabled when system mods are applied (ppy#36913)

Closes ppy#36906.

---------

Co-authored-by: Bartłomiej Dach <dach.bartlomiej@gmail.com>

Author: peppy

osu.Game.Tests/Visual/UserInterface/TestSceneModSelectOverlay.cs

@@ -698,6 +698,35 @@ public void TestDeselectAllViaKey_WithSearchApplied()
             AddUntilStep("all mods deselected", () => !SelectedMods.Value.Any());
         }
 
+        [Test]
+        public void TestTouchDeviceDoesNotInterfereWithDeselectAll()
+        {
+            createScreen();
+            changeRuleset(0);
+
+            AddAssert("deselect all button disabled", () => !this.ChildrenOfType<DeselectAllModsButton>().Single().Enabled.Value);
+
+            AddStep("select TD", () => SelectedMods.Value = new Mod[] { new OsuModTouchDevice() });
+            AddAssert("deselect all button still disabled", () => !this.ChildrenOfType<DeselectAllModsButton>().Single().Enabled.Value);
+
+            AddStep("click deselect all button", () =>
+            {
+                InputManager.MoveMouseTo(this.ChildrenOfType<DeselectAllModsButton>().Single());
+                InputManager.Click(MouseButton.Left);
+            });
+
+            AddUntilStep("touch mod still present", () => SelectedMods.Value, () => Is.EqualTo(new Mod[] { new OsuModTouchDevice() }));
+
+            AddStep("select NC + TD", () => SelectedMods.Value = new Mod[] { new OsuModTouchDevice(), new OsuModNightcore() });
+            AddStep("click deselect all button", () =>
+            {
+                InputManager.MoveMouseTo(this.ChildrenOfType<DeselectAllModsButton>().Single());
+                InputManager.Click(MouseButton.Left);
+            });
+
+            AddUntilStep("touch mod still present", () => SelectedMods.Value, () => Is.EqualTo(new Mod[] { new OsuModTouchDevice() }));
+        }
+
         [Test]
         public void TestDeselectAllViaButton()
         {

osu.Game/Overlays/Mods/DeselectAllModsButton.cs

@@ -33,7 +33,7 @@ protected override void LoadComplete()
 
         private void updateEnabledState()
         {
-            Enabled.Value = selectedMods.Value.Any();
+            Enabled.Value = selectedMods.Value.Any(m => m.Type != ModType.System);
         }
     }
 }