how can I customize lualine for nvimtree

[kristoph]

How can I customize the lualine sections for NvimTree? I can disable lualine for nvimtree by using the NvimTree filetype in the disabled filetypes. But if I attempt to use the same filetype as an extension:

        extensions = {
          filetypes = { 'NvimTree' },
          sections = {
            lualine_a = { 'mode' },
            lualine_b = { 'branch', 'diff', 'diagnostics' },
            lualine_c = {},
            lualine_x = {},
            lualine_y = {},
            lualine_z = {}
          }
        },

This does not work ( I still get the globally setup sections ).

( many thanks for any help. )