FIX: OnMouseUpAsButton dropped in Play mode on Game view focus change

Focus events (engine >= 6000.5.0a8) cause an InputUpdateType.Editor update to run in
Play mode when the Game view focus changes. FinalizeUpdate drove the legacy
SendMouseEvents pipeline from that editor update, where Pointer.current reflects the
editor state buffer (position (0,0), not pressed). That produced a spurious mouse-up
that cleared the press target, so OnMouseUpAsButton/OnMouseUp were skipped on the real
release. Guard the legacy mouse send so it does not run for InputUpdateType.Editor
updates (consistent with existing guards in this file). Focus-event delivery is
unaffected. Covered by CoreTests.MouseEvents_CanReceiveOnMouseUpAsButton.

Author: LeoUnity

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -31,6 +31,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an incorrect ArraysHelper.HaveDuplicateReferences implementation that didn't use its arguments right [ISXB-1792] (https://github.com/Unity-Technologies/InputSystem/pull/2376)
 - Fixed `InputAction.IsPressed`, `WasPressedThisFrame`, and `WasReleasedThisFrame` using a `ButtonControl`'s `pressPoint` when a binding also had an explicit `PressInteraction` with its own `pressPoint`, which could make those APIs disagree with the interaction's press and release behavior. Action-level press APIs now follow the interaction threshold when both are set explicitly.
 - Fixed `IndexOutOfRangeException` in `InputDeviceBuilder` when connecting an HID gamepad whose report descriptor declares a hat switch with Report Size 8 (e.g. ESP32-BLE-Gamepad). The HID layer now anchors the hat's directional sub-controls to the hat's own byte instead of letting the layout system auto-allocate a fresh byte for each [UUM-143659](https://jira.unity3d.com/browse/UUM-143659).
+- Fixed `OnMouseUpAsButton` and `OnMouseUp` being dropped in Play mode when the Game view's focus changes between a press and its release on Unity 6000.5.0a8 and newer. The legacy `SendMouseEvents` pipeline is no longer driven from `InputUpdateType.Editor` updates, which read the editor state buffer (position (0,0), not pressed) and produced a spurious mouse release that cleared the press target.
 
 ### Changed
 - Action-level `IsPressed`, `WasPressedThisFrame`, and `WasReleasedThisFrame` for bindings to `Vector2Control` / `StickControl` no longer consult a per-control `pressPoint` on the vector (that field was removed). Use a `Press` interaction to set a custom threshold, or rely on `defaultButtonPressPoint`.

Packages/com.unity.inputsystem/InputSystem/Runtime/InputManager.cs

@@ -4069,7 +4069,9 @@ private void FinalizeUpdate(InputUpdateType updateType)
             //send pointer data to backend for OnMouseEvents
 #if UNITY_INPUTSYSTEM_SUPPORTS_MOUSE_SCRIPT_EVENTS
             var pointer = Pointer.current;
-            if (pointer != null && pointer.added && gameIsPlaying)
+            // Skip during InputUpdateType.Editor: pointer reads the editor state buffer (position (0,0), not pressed),
+            // which would emit a spurious release and drop OnMouseUp/OnMouseUpAsButton on the real release.
+            if (pointer != null && pointer.added && gameIsPlaying && updateType != InputUpdateType.Editor)
                 NativeInputSystem.DoSendMouseEvents(pointer.press.isPressed, pointer.press.wasPressedThisFrame, pointer.position.x.value, pointer.position.y.value);
 #endif
             m_CurrentUpdate = default;