how to style one particular treeview

I am using one particular ttk::treeview as a listbox:

    ttk::frame .ignoresForm.ignoresListFrame
    set ignoresList [ttk::treeview \
        .ignoresForm.ignoresListFrame.ignoresList -striped true \
        -yscrollcommand {.ignoresForm.ignoresListFrame.scrolly set}]
    ttk::style configure List.Treeview -indent 0
    #ttk::style map List.Treeview -indent [list disabled 0 active 0]
    $ignoresList configure -show tree -selectmode browse \
        -style List.Treeview
    $ignoresList column #0 -anchor w -stretch true
    ttk::scrollbar .ignoresForm.ignoresListFrame.scrolly -orient vertical \
        -command {.ignoresForm.ignoresListFrame.ignoresList yview}

By default a ttk::treeview has an -indent of 20 pixels which makes sense
for trees but is not needed for lists.

In the code above I've tried to create a custom style to apply to one
treeview but it has no effect whether I use ttk::style configure or
ttk::style map.

What is the correct way to do this?