[CONNECT C++] Dialog Layout Manager

Some example MicroStationAPI apps have dialog definitions with auto layout management.  For example...

CmdItemListRsc          ItemList_ECSChemaExample =
    {{
    BEGIN_VSTACK_LAYOUT(VSTACKLAYOUTID_ToolSettingsMain,"")
        BEGIN_HSTACK_LAYOUT(0, "")
            STRETCH(1)
            BEGIN_VSTACK_LAYOUT(0, "")
                BEGIN_GRID_LAYOUT(GRIDLAYOUTID_3ColumnsInner, "marginBottom='10'")
                    GRID_ROW(0, "")
                        LAYOUT_LABEL_NEXT_RIGHT(8*XC, "")
                        {{AUTO_XY, 51*XC, 0},     Text,           TEXTID_Processfile,        ON, 0, "", ""},
                        {AUTO_XYWH,                         IconCmdX,       ICONCMDID_BrowseFile,      ON, 0, "", ""},
                    END_ROW
                END_LAYOUT
                {{0, 0, 0, 50*YC},  Tree,        TREEID_ContentList,                  ON, 0, "", ""},
            END_LAYOUT
            STRETCH(1)
        END_LAYOUT

        STRETCH(1)
    END_LAYOUT
    }};

Is there a guide to help us through that maze of macros?