Use position, not the ID, to find the native menu items to allow the code in wxMenuItem::SetItemLabel() and DoSetBitmap() to also work with submenus and not just the normal items. Closes #16246. [This is the backport of r76676 from trunk.] git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@77945 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775