Don't update position variables from window dragging code.
Let "configure-event" handler do it so it can also generate proper move events.
closes #15904


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75826 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775