Page up/down behaviour now takes into account margins and scale
GetTextForRange takes composites into account properly
HasCharacterAttributes correction


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@77980 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775