ED_view3d_init_mats_rv3d was calling glMultMatrixf() which was mostly harmless but could also lead to confusing bugs (2 reported previously).
Looked into this and every call to ED_view3d_init_mats_rv3d except for object drawing, doesn't need this so made a second version of ED_view3d_init_mats_rv3d - ED_view3d_init_mats_rv3d_gl which does the matrix multiplication, remove confusing checks in selection code.