winapi cursor state improvements

Editor/main_Windows.cpp

@@ -303,6 +303,25 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
     case WM_DESTROY:
 		PostQuitMessage(0);
         break;
+	case WM_SETCURSOR:
+		switch (LOWORD(lParam))
+		{
+		case HTBOTTOM:
+		case HTBOTTOMLEFT:
+		case HTBOTTOMRIGHT:
+		case HTLEFT:
+		case HTRIGHT:
+		case HTTOP:
+		case HTTOPLEFT:
+		case HTTOPRIGHT:
+			// allow the system to handle these window resize cursors:
+			return DefWindowProc(hWnd, message, wParam, lParam);
+		default:
+			// notify the engine at other cursor changes to set its own cursor instead
+			wi::input::NotifyCursorChanged();
+			break;
+		}
+		break;
     default:
         return DefWindowProc(hWnd, message, wParam, lParam);
     }