ListBrowser layout question

I'm currently giving the final touches to the MultiRename tool which I've been working on for some time. It uses a ListBrowser in a very prominent position in the main window. Here's a

I would like to change the three columns so that the left column, “State”, has the minimum required size and the other two columns, “Old name” and “New name”, share the remaining space.

Currently the ListView ist set up like this:

...
      LAYOUT_AddChild, m_ppGadgets[GID_LBR_PROCESSING_LIST] = NewObject(LISTBROWSER_GetClass(), NULL,
        GA_ID, GID_LBR_PROCESSING_LIST,
        GA_RelVerify, TRUE,
        LISTBROWSER_AutoFit, TRUE,
        LISTBROWSER_ColumnInfo, (ULONG)m_pColumnInfo,
        LISTBROWSER_ColumnTitles, TRUE,
        LISTBROWSER_HorizontalProp, TRUE,
        LISTBROWSER_TitleClickable, TRUE,
      TAG_DONE),
...

and m_pColumnInfo created like:

  m_pColumnInfo = AllocLBColumnInfo(3,
                                    LBCIA_Column, 0,
                                      LBCIA_Sortable, FALSE,
                                      LBCIA_Title, "State",
                                    LBCIA_Column, 1,
                                      LBCIA_AutoSort, TRUE,
                                      LBCIA_SortArrow, TRUE,
                                      LBCIA_SortDirection, LBMSORT_FORWARD,
                                      LBCIA_Title, "Old name",
                                    LBCIA_Column, 2,
                                      LBCIA_Sortable, FALSE,
                                      LBCIA_Title, "New name",
                                    TAG_DONE);

In the Autodocs it reads, that columns are weighted by default, and so far I have not made any other setting.

So, how to change it for the first column to get the width that it needs and the other two columns share the remaining space 50/50?