Background: Currently vba streams ( and import of some controls ) are imported in 2 places.

1) The legacy filters

   a) VBA Streams
       * filter/source/msfilter/msvbasic.cxx
       * filter/source/msfilter/svxmsbas.cxx
       * filter/source/msfilter/svxmsbas2.cxx
   b) OCX controls
       * filter/source/msfilter/msocximex.cxx

2) The new oox filter

   a) VBA Streams
       * oox/source/ole/vbahelper.cxx
       * oox/source/ole/vbaproject.cxx
       * oox/source/ole/vbamodule.cxx
   b) OCX controls
       * oox/source/ole/vbacontrol.cxx
       * oox/source/ole/axcontrol.cxx

Calc now only uses the oox filter for both importing vba project streams and additionally for OCX controls. The idea is to propagate similar changes throughout the code in order to completely remove those source files ( msvbasic.cxx, svxmsbas.cxx, svxmsba2.cxx & msocximex,cxx ). There are some hints the patch http://cgit.freedesktop.org/libreoffice/build/tree/patches/vba/vba-use-ooxfilter-forcontrols.diff which at least at one point removed the dependency on on the legacy filter from word ( note: that patch is completely out of date but still contains useful pointers especially in terms of where the code needs to be changed )

Skills: building, debugging, C++, UNO, patch reading