diff --git a/README b/README
index 7171e74..2f3efa7 100644
--- a/README
+++ b/README
@@ -3,6 +3,8 @@ $Id$
 
 Read the INSTALL file, manual page and source code for more information.
 
+iftop must be run as root.
+
 RedHat 7.2 users:
 There is a bug in the version of ncurses distibuted with RedHat 7.2 that
 will cause iftop to segfault.  The RPM in RedHat's Rawhide distribution
diff --git a/TODO b/TODO
index 1673241..cde3c89 100644
--- a/TODO
+++ b/TODO
@@ -12,10 +12,6 @@ $Id$
 
 * Aggregate traffic by source host / dest host rather than just by host pair.
 
-* Cummulative byte counters.
-
 * Configurable sort criteria.
 
 * Configurable refresh rates.
-
-* Ability to turn bar graphs on and off.
diff --git a/iftop.c b/iftop.c
index 244f73d..81e36fd 100644
--- a/iftop.c
+++ b/iftop.c
@@ -87,7 +87,7 @@ void history_rotate() {
 }
 
 
-void tick() {
+void tick(int print) {
     time_t t;
 
     pthread_mutex_lock(&tick_mutex);
@@ -95,10 +95,14 @@ void tick() {
     t = time(NULL);
     if(t - last_timestamp >= RESOLUTION) {
         //printf("TICKING\n");
+	analyse_data();
         ui_print();
         history_rotate();
         last_timestamp = t;
     }
+    else if(print) {
+	ui_print();
+    }
 
     pthread_mutex_unlock(&tick_mutex);
 }
@@ -115,7 +119,7 @@ static void handle_packet(char* args, const struct pcap_pkthdr* pkthdr,const cha
     int direction = 0; /* incoming */
     eptr = (struct ether_header*)packet;
        
-    tick();
+    tick(0);
     
     if(ntohs(eptr->ether_type) == ETHERTYPE_IP) {
         struct ip* iptr;
@@ -285,6 +289,8 @@ int main(int argc, char **argv) {
 
     init_history();
 
+    ui_init();
+
     pthread_create(&thread, NULL, (void*)&packet_loop, NULL);
 
     ui_loop();
diff --git a/ui.c b/ui.c
index 0f6f995..03f5113 100644
--- a/ui.c
+++ b/ui.c
@@ -41,6 +41,10 @@ extern options_t options ;
 
 void ui_finish();
 
+sorted_list_type screen_list;
+host_pair_line totals;
+int peaksent, peakrecv, peaktotal;
+
 int screen_line_compare(void* a, void* b) {
     int i;
     host_pair_line* aa = (host_pair_line*)a;
@@ -149,43 +153,28 @@ void draw_totals(host_pair_line* totals) {
 
 extern history_type history_totals;
 
-
-void ui_print() {
-    hash_node_type* n = NULL;
-    sorted_list_node* nn = NULL;
-    char hostname[HOSTNAME_LENGTH];
-    static char *line;
-    static int lcols;
-    int peaksent = 0, peakrecv = 0, peaktotal = 0;
-    int y = 1;
-    int i;
-    sorted_list_type screen_list;
-    host_pair_line totals;
-
-    if (!line || lcols != COLS) {
-        xfree(line);
-        line = calloc(COLS + 1, 1);
-    }
-
+void screen_list_init() {
     screen_list.compare = &screen_line_compare;
     sorted_list_initialise(&screen_list);
+}
 
-    clear();
-    //erase();
-    move(0, 0);
-    attron(A_REVERSE);
-    addstr(" Q ");
-    attroff(A_REVERSE);
-    addstr(" quit ");
-    attron(A_REVERSE);
-    addstr(" R ");
-    attroff(A_REVERSE);
-    addstr(options.dnsresolution ? " name resolution off "
-                         : " name resolution on  ");
-    draw_bar_scale(&y);
+void screen_data_clear() {
+    sorted_list_node* nn = NULL;
+    peaksent = peakrecv = peaktotal = 0;
+    while((nn = sorted_list_next_item(&screen_list, nn)) != NULL) {
+        free(nn->data);
+    }
+    sorted_list_destroy(&screen_list);
+}
+
+void analyse_data() {
+    hash_node_type* n = NULL;
+    int i;
 
     memset(&totals, 0, sizeof totals);
 
+    screen_data_clear();
+
     while(hash_next_item(history, &n) == HASH_STATUS_OK) {
         history_type* d = (history_type*)n->rec;
         host_pair_line* screen_line;
@@ -235,6 +224,36 @@ void ui_print() {
         }
     }
 
+}
+
+void ui_print() {
+    sorted_list_node* nn = NULL;
+    char hostname[HOSTNAME_LENGTH];
+    static char *line;
+    static int lcols;
+    int y = 1;
+
+    if (!line || lcols != COLS) {
+        xfree(line);
+        line = calloc(COLS + 1, 1);
+    }
+
+
+    clear();
+    //erase();
+    move(0, 0);
+    attron(A_REVERSE);
+    addstr(" Q ");
+    attroff(A_REVERSE);
+    addstr(" quit ");
+    attron(A_REVERSE);
+    addstr(" R ");
+    attroff(A_REVERSE);
+    addstr(options.dnsresolution ? " name resolution off "
+                         : " name resolution on  ");
+    draw_bar_scale(&y);
+
+
 
     /* Screen layout: we have 2 * HISTORY_DIVISIONS 6-character wide history
      * items, and so can use COLS - 12 * HISTORY_DIVISIONS to print the two
@@ -274,7 +293,6 @@ void ui_print() {
 
         }
         y += 2;
-        free(screen_line);
     }
 
 
@@ -316,14 +334,9 @@ void ui_print() {
     
     refresh();
 
-    sorted_list_destroy(&screen_list);
 }
 
-void ui_loop() {
-    pthread_mutex_t tick_wait_mutex;
-    pthread_cond_t tick_wait_cond;
-    extern sig_atomic_t foad;
-
+void ui_init() {
     (void) initscr();      /* initialize the curses library */
     keypad(stdscr, TRUE);  /* enable keyboard mapping */
     (void) nonl();         /* tell curses not to do NL->CR/NL on output */
@@ -332,9 +345,12 @@ void ui_loop() {
     halfdelay(2);
 
     erase();
-    
-    pthread_mutex_init(&tick_wait_mutex, NULL);
-    pthread_cond_init(&tick_wait_cond, NULL);
+
+    screen_list_init();
+}
+
+void ui_loop() {
+    extern sig_atomic_t foad;
     while(foad == 0) {
         int i;
         i = toupper(getch());
@@ -345,13 +361,15 @@ void ui_loop() {
 
             case 'R':
                 options.dnsresolution = !options.dnsresolution;
+                tick(1);
                 break;
 
 	        case 'B':
                 options.showbars = !options.showbars; 
+                tick(1);
                 break;
         }
-        tick();
+        tick(0);
     }
 }