Function lv_buttonmatrix_set_button_ctrl 

pub unsafe extern "C" fn lv_buttonmatrix_set_button_ctrl(
    obj: *mut lv_obj_t,
    btn_id: u32,
    ctrl: lv_buttonmatrix_ctrl_t,
)

Set the attributes of a button of the button matrix @param obj pointer to button matrix object @param btn_id 0 based index of the button to modify. (Not counting new lines) @param ctrl OR-ed attributes. E.g. LV_BUTTONMATRIX_CTRL_NO_REPEAT | LV_BUTTONMATRIX_CTRL_CHECKABLE