FIX: ISXB-1343 show dialog for unsaved changes (#2124)

Author: smnwttbr

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -10,7 +10,8 @@ however, it has to be formatted properly to pass verification tests.
 
 ## [Unreleased] - yyyy-mm-dd
 
-
+- Fixed an issue causing a number of errors to be displayed when using `InputTestFixture` in playmode tests with domain reloading disabled on playmode entry. [ISXB-1446](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1446)
+- Fixed issue where user was not prompted to save changes when loading a second input actions asset into an already opened editor. [ISXB-1343](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1343)
 
 ## [1.14.0] - 2025-03-20
 
@@ -19,7 +20,6 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed an issue where ButtonStates are not fully updated when switching SingleUnifiedPointer. [ISXB-1356](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1356)
 - Fixed errors when pasting composite parts into non-composites. [ISXB-757](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-757)
 - Fixed an issue where updating the InputSystem outside of the dynamic Update would lead to UI input and navigation events get lost. [ISXB-1313](https://issuetracker.unity3d.com/issues/ui-onclick-events-sometimes-do-not-trigger-when-manual-update-is-utilized-with-input-system)
-- Fixed an issue causing a number of errors to be displayed when using `InputTestFixture` in playmode tests with domain reloading disabled on playmode entry [ISXB-1446](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1446)
 
 ### Changed
 - Changed enum value `Key.IMESelected` to obsolete which was not a real key. Please use the ButtonControl `imeSelected`.

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/InputActionsEditorWindow.cs

@@ -100,6 +100,28 @@ private static InputActionsEditorWindow OpenWindow(InputActionAsset asset, strin
             }
 
             var window = GetWindow<InputActionsEditorWindow>();
+            if (window.m_IsDirty)
+            {
+                var assetPath = AssetDatabase.GUIDToAssetPath(window.m_AssetGUID);
+                if (!string.IsNullOrEmpty(assetPath))
+                {
+                    // Prompt user with a dialog
+                    var result = Dialog.InputActionAsset.ShowSaveChanges(assetPath);
+                    switch (result)
+                    {
+                        case Dialog.Result.Save:
+                            window.Save(isAutoSave: false);
+                            break;
+                        case Dialog.Result.Cancel:
+                            return window;
+                        case Dialog.Result.Discard:
+                            break;
+                        default:
+                            throw new ArgumentOutOfRangeException(nameof(result));
+                    }
+                }
+            }
+
             window.m_IsDirty = false;
             window.minSize = k_MinWindowSize;
             window.SetAsset(asset, actionToSelect, actionMapToSelect);