Fix restoring locked cursor state when window gains focus again

Source/Editor/Windows/GameWindow.cs

@@ -1179,9 +1179,10 @@ namespace FlaxEditor.Windows
                 _cursorVisible = Screen.CursorVisible;
                 _cursorLockMode = Screen.CursorLock;
 
-                // Restore cursor visibility (could be hidden by the game)
+                // Restore cursor state, could be hidden or locked by the game
                 if (!_cursorVisible)
                     Screen.CursorVisible = true;
+                Screen.CursorLock = CursorLockMode.None;
             }
         }
 

Source/Engine/Input/Mouse.h

@@ -119,7 +119,8 @@ public:
     /// <summary>
     /// Gets the current state of mouse relative mode. 
     /// </summary>
-    API_FUNCTION() FORCE_INLINE bool IsRelative() const
+    /// <param name="window">The window to check against, or null to check for any window.</param>
+    virtual API_FUNCTION() bool IsRelative(Window* window = nullptr) const
     {
         return _relativeMode;
     }

Source/Engine/Platform/Base/WindowBase.h

@@ -45,6 +45,7 @@ protected:
     bool _isHorizontalFlippingMouse = false;
     bool _isVerticalFlippingMouse = false;
     bool _isClippingCursor = false;
+    bool _restoreRelativeMode = false;
 
     explicit WindowBase(const CreateWindowSettings& settings);
     virtual ~WindowBase();

Source/Engine/Platform/SDL/SDLInput.cpp

@@ -432,6 +432,13 @@ public:
         if (!SDL_SetWindowRelativeMouseMode(windowHandle, relativeMode))
             LOG(Error, "Failed to set mouse relative mode: {0}", String(SDL_GetError()));
     }
+
+    bool IsRelative(Window* window) const override
+    {
+        if (window == nullptr)
+            return _relativeMode;
+        return _relativeModeWindow == window && _relativeMode;
+    }
 };
 
 /// <summary>

Source/Engine/Platform/SDL/SDLWindow.cpp

@@ -440,6 +440,9 @@ void SDLWindow::HandleEvent(SDL_Event& event)
             if (inRelativeMode)
                 Input::Mouse->SetRelativeMode(true, this);
         }
+        else if (_restoreRelativeMode)
+            Input::Mouse->SetRelativeMode(true, this);
+        _restoreRelativeMode = false;
         return;
     }
     case SDL_EVENT_WINDOW_FOCUS_LOST:
@@ -448,6 +451,13 @@ void SDLWindow::HandleEvent(SDL_Event& event)
             SDL_StopTextInput(_window);
         if (_isClippingCursor)
             SDL_SetWindowMouseRect(_window, nullptr);
+
+        if (Input::Mouse->IsRelative(this))
+        {
+            Input::Mouse->SetRelativeMode(false, this);
+            _restoreRelativeMode = true;
+        }
+
         OnLostFocus();
         return;
     }