ttk::menubutton on macOS

Hi,
using the following script, there's a kind of white area around the ttk::menubutton.
Do you know how to get this area the same colour as its parent frame?

many thanks,
Nicolas


package require Tk

ttk::style configure mini.TMenubutton  -width 5 -relief none
ttk::style configure mini.TMenubutton -foreground black
ttk::style map mini.TMenubutton -background [list {active disabled readonly} green]

frame .f -background green
set thisMenu [menu .m]
for {set i 1} {$i <= 10} {incr i} {
    $thisMenu add command -label $i -command "puts $i"
}
ttk::menubutton .f.m -style mini.TMenubutton  -direction below -menu .m -text "Hi"

grid .f.m -sticky news -padx 10 -pady 10
grid rowconfigure .f all -weight 1
grid columnconfigure .f all -weight 1
grid .f -sticky news