Show babysteps on the LCD in mm, not steps

Marlin/ultralcd.cpp

 
   #if ENABLED(BABYSTEPPING)
 
-    int babysteps_done = 0;
+    long babysteps_done = 0;
 
     static void _lcd_babystep(const AxisEnum axis, const char* msg) {
       ENCODER_DIRECTION_NORMAL();
       if (encoderPosition) {
-        int distance = (int32_t)encoderPosition * BABYSTEP_MULTIPLICATOR;
+        int babystep_increment = (int32_t)encoderPosition * BABYSTEP_MULTIPLICATOR;
         encoderPosition = 0;
         lcdDrawUpdate = LCDVIEW_REDRAW_NOW;
-        thermalManager.babystep_axis(axis, distance);
-        babysteps_done += distance;
+        thermalManager.babystep_axis(axis, babystep_increment);
+        babysteps_done += babystep_increment;
       }
-      if (lcdDrawUpdate) lcd_implementation_drawedit(msg, itostr3sign(babysteps_done));
+      if (lcdDrawUpdate)
+        lcd_implementation_drawedit(msg, ftostr43sign(
+          ((1000 * babysteps_done) / planner.axis_steps_per_mm[axis]) * 0.001f
+        ));
       if (LCD_CLICKED) lcd_goto_previous_menu(true);
     }