diff --git a/plot.c b/plot.c
index fe167ea..9d314fa 100644
--- a/plot.c
+++ b/plot.c
@@ -12,9 +12,6 @@ void frequency_string(char *buf, size_t len, uint32_t freq, char *prefix);
 void frequency_string_short(char *buf, size_t len, int32_t freq, char prefix);
 void markmap_all_markers(void);
 
-//#define GRID_COLOR 0x0863
-//uint16_t grid_color = 0x1084;
-
 /* indicate dirty cells */
 uint16_t markmap[2][8];
 uint16_t current_mappage = 0;
@@ -294,16 +291,16 @@ smith_grid2(int x, int y, float scale)
 #endif
 
 const int cirs[][4] = {
-		  { 0, 58/2, 58/2, 0 },    // Constant Reactance Circle: 2j : R/2 = 58
-		  { 29/2, 0, 29/2, 1 },    // Constant Resistance Circle: 3 : R/4 = 29
-		  { 0, 115/2, 115/2, 0 },  // Constant Reactance Circle: 1j : R = 115
-		  { 58/2, 0, 58/2, 1 },    // Constant Resistance Circle: 1 : R/2 = 58
-		  { 0, 230/2, 230/2, 0 },  // Constant Reactance Circle: 1/2j : R*2 = 230
-		  { 86/2, 0, 86/2, 1 },    // Constant Resistance Circle: 1/3 : R*3/4 = 86
-		  { 0, 460/2, 460/2, 0 },  // Constant Reactance Circle: 1/4j : R*4 = 460
-		  { 115/2, 0, 115/2, 1 },  // Constant Resistance Circle: 0 : R
-		  { 173/2, 0, 173/2, 1 },  // Constant Resistance Circle: -1/3 : R*3/2 = 173
-		  { 0, 0, 0, 0 } // sentinel
+  { 0, 58/2, 58/2, 0 },    // Constant Reactance Circle: 2j : R/2 = 58
+  { 29/2, 0, 29/2, 1 },    // Constant Resistance Circle: 3 : R/4 = 29
+  { 0, 115/2, 115/2, 0 },  // Constant Reactance Circle: 1j : R = 115
+  { 58/2, 0, 58/2, 1 },    // Constant Resistance Circle: 1 : R/2 = 58
+  { 0, 230/2, 230/2, 0 },  // Constant Reactance Circle: 1/2j : R*2 = 230
+  { 86/2, 0, 86/2, 1 },    // Constant Resistance Circle: 1/3 : R*3/4 = 86
+  { 0, 460/2, 460/2, 0 },  // Constant Reactance Circle: 1/4j : R*4 = 460
+  { 115/2, 0, 115/2, 1 },  // Constant Resistance Circle: 0 : R
+  { 173/2, 0, 173/2, 1 },  // Constant Resistance Circle: -1/3 : R*3/2 = 173
+  { 0, 0, 0, 0 } // sentinel
 };  
 
 int
@@ -500,18 +497,6 @@ cartesian_scale(float re, float im, int *xp, int *yp, float scale)
 float
 groupdelay_from_array(int i, float array[POINTS_COUNT][2])
 {
-/*
-  if (i == 0) {
-    float deltaf = frequencies[1] - frequencies[0];
-    return groupdelay(array[0], array[1], deltaf);
-  } else if (i == 100) {
-    float deltaf = frequencies[i] - frequencies[i-1];
-    return groupdelay(array[i-1], array[i], deltaf);
-  } else {
-    float deltaf = frequencies[i+1] - frequencies[i-1];
-    return groupdelay(array[i-1], array[i+1], deltaf);
-  }
-*/
   int bottom = (i ==   0) ?   0 : i - 1;
   int top    = (i == POINTS_COUNT-1) ? POINTS_COUNT-1 : i + 1;
   float deltaf = frequencies[top] - frequencies[bottom];
diff --git a/ui.c b/ui.c
index f52b74a..31f9b19 100644
--- a/ui.c
+++ b/ui.c
@@ -33,7 +33,6 @@ uistat_t uistat = {
  marker_delta: FALSE,
 };
 
-
 #define NO_EVENT					0
 #define EVT_BUTTON_SINGLE_CLICK		0x01
 #define EVT_BUTTON_DOUBLE_CLICK		0x02
@@ -72,9 +71,9 @@ enum {
   KM_START, KM_STOP, KM_CENTER, KM_SPAN, KM_CW, KM_SCALE, KM_REFPOS, KM_EDELAY, KM_VELOCITY_FACTOR, KM_SCALEDELAY
 };
 
-uint8_t ui_mode = UI_NORMAL;
-uint8_t keypad_mode;
-int8_t selection = 0;
+static uint8_t ui_mode = UI_NORMAL;
+static uint8_t keypad_mode;
+static int8_t  selection = 0;
 
 // Set structure align as WORD (save flash memory)
 #pragma pack(push, 2)
@@ -86,9 +85,11 @@ typedef struct {
 } menuitem_t;
 #pragma pack(pop)
 
-int8_t last_touch_status = FALSE;
-int16_t last_touch_x;
-int16_t last_touch_y;
+// Touch screen
+static int8_t last_touch_status = FALSE;
+static int16_t last_touch_x;
+static int16_t last_touch_y;
+
 //int16_t touch_cal[4] = { 1000, 1000, 10*16, 12*16 };
 //int16_t touch_cal[4] = { 620, 600, 130, 180 };
 #define EVT_TOUCH_NONE 0
@@ -108,7 +109,6 @@ int awd_count;
 char kp_buf[11];
 int8_t kp_index = 0;
 
-
 void ui_mode_normal(void);
 void ui_mode_menu(void);
 void ui_mode_numeric(int _keypad_mode);
@@ -439,7 +439,6 @@ enter_dfu(void)
   NVIC_SystemReset();
 }
 
-
 // type of menu item 
 enum {
   MT_NONE,
@@ -574,6 +573,7 @@ choose_active_trace(void)
 static void
 menu_trace_cb(int item, uint8_t data)
 {
+  (void)item;
   if (trace[data].enabled) {
     if (data == uistat.current_trace) {
       // disable if active trace is selected
@@ -581,11 +581,11 @@ menu_trace_cb(int item, uint8_t data)
       choose_active_trace();
     } else {
       // make active selected trace
-      uistat.current_trace = item;
+      uistat.current_trace = data;
     }
   } else {
     trace[data].enabled = TRUE;
-    uistat.current_trace = item;
+    uistat.current_trace = data;
   }
   request_to_redraw_grid();
   draw_menu();
@@ -740,7 +740,7 @@ menu_marker_op_cb(int item, uint8_t data)
       if (previous_marker == -1 || active_marker == previous_marker) {
         // if only 1 marker is active, keep center freq and make span the marker comes to the edge
         uint32_t center = get_sweep_frequency(ST_CENTER);
-        uint32_t span = center > freq ? center - freq : freq - center;
+        uint32_t span = get_sweep_frequency(ST_SPAN);
         set_sweep_frequency(ST_SPAN, span * 2);
       } else {
         // if 2 or more marker active, set start and stop freq to each marker
@@ -1480,8 +1480,7 @@ erase_menu_buttons(void)
 void
 erase_numeric_input(void)
 {
-  uint16_t bg = 0;
-  ili9341_fill(0, 240-32, 320, 32, bg);
+  ili9341_fill(0, 240-32, 320, 32, DEFAULT_BG_COLOR);
 }
 
 void
@@ -1571,7 +1570,7 @@ void set_numeric_value(void)
     set_electrical_delay(uistat.value);
     break;
   case KM_VELOCITY_FACTOR:
-    velocity_factor = uistat.value;
+    velocity_factor = uistat.value/100.0;
     break;
   }
 }
@@ -1584,7 +1583,6 @@ draw_numeric_area(void)
   draw_numeric_input(buf);
 }
 
-
 void
 ui_mode_menu(void)
 {
@@ -1718,12 +1716,11 @@ lever_zoom_span(int status)
   uint32_t span = get_sweep_frequency(ST_SPAN);
   if (status & EVT_UP) {
     span = step_round(span - 1);
-    set_sweep_frequency(ST_SPAN, span);
   } else if (status & EVT_DOWN) {
     span = step_round(span + 1);
     span = step_round(span * 3);
-    set_sweep_frequency(ST_SPAN, span);
   }
+  set_sweep_frequency(ST_SPAN, span);
 }
 
 static void