Restricts horizontal scrolling to mouse over

Ensures horizontal mouse wheel events only affect the ScrollViewer when the mouse cursor is directly over it. This prevents unintended scrolling of background or non-focused elements.

Simplifies the scroll handling by inlining the logic and removing a redundant helper method.

Author: Keboo

src/MaterialDesignThemes.Wpf/ScrollViewerAssist.cs

@@ -140,18 +140,13 @@ IntPtr Hook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled
                 const int WM_MOUSEHWHEEL = 0x020E;
                 switch (msg)
                 {
-                    case WM_MOUSEHWHEEL:
+                    case WM_MOUSEHWHEEL when scrollViewer.IsMouseOver:
                         int tilt = (short)((wParam.ToInt64() >> 16) & 0xFFFF);
-                        OnMouseTilt(tilt);
+                        scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + tilt);
                         return (IntPtr)1;
                 }
                 return IntPtr.Zero;
             }
-
-            void OnMouseTilt(int tilt)
-            {
-                scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + tilt);
-            }
         }
     }