diff --git a/example/src/components/gantt-table.tsx b/example/src/components/gantt-table.tsx
index a38ed05..5687115 100644
--- a/example/src/components/gantt-table.tsx
+++ b/example/src/components/gantt-table.tsx
@@ -26,38 +26,6 @@ export const GanttTableExample: React.SFC<GanttTableExampleProps> = props => {
     options.columnWidth = 250;
   }
 
-  const [tasks, setTasks] = React.useState(props.tasks);
-  const onTaskDateChange = async (task: Task) => {
-    if (props.onDateChange) {
-      try {
-        await props.onDateChange(task);
-      } catch (e) {
-        throw e;
-      }
-      setTasks(tasks.map(t => (t.id === task.id ? task : t)));
-    }
-  };
-
-  const onTaskProgressChange = async (task: Task) => {
-    if (props.onProgressChange) {
-      try {
-        await props.onProgressChange(task);
-      } catch (e) {
-        setTasks(props.tasks.slice());
-        throw e;
-      }
-
-      setTasks(tasks.map(t => (t.id === task.id ? task : t)));
-    }
-  };
-
-  const onTaskItemDelete = async (task: Task) => {
-    if (props.onTaskDelete) {
-      await props.onTaskDelete(task);
-      setTasks(tasks.filter(t => t.id !== task.id));
-    }
-  };
-
   return (
     <div className="Wrapper">
       <div
@@ -107,7 +75,7 @@ export const GanttTableExample: React.SFC<GanttTableExampleProps> = props => {
             To
           </div>
         </div>
-        {tasks.map(t => {
+        {props.tasks.map(t => {
           return (
             <div
               className="GanttTable-row"
@@ -121,14 +89,7 @@ export const GanttTableExample: React.SFC<GanttTableExampleProps> = props => {
         })}
       </div>
       <div style={{ overflowX: "scroll" }}>
-        <Gantt
-          {...options}
-          {...props}
-          tasks={tasks}
-          onDateChange={onTaskDateChange}
-          onTaskDelete={onTaskItemDelete}
-          onProgressChange={onTaskProgressChange}
-        />
+        <Gantt {...props} {...options} />
       </div>
     </div>
   );
diff --git a/src/components/Bar/bar.tsx b/src/components/Bar/bar.tsx
index 7f2eb7f..e32c698 100644
--- a/src/components/Bar/bar.tsx
+++ b/src/components/Bar/bar.tsx
@@ -1,5 +1,4 @@
 import React, { useState } from "react";
-import { Task } from "../../types/public-types";
 import { BarProgressHandle } from "./bar-progress-handle";
 import { BarDateHandle } from "./bar-date-handle";
 import { BarDisplay } from "./bar-display";
@@ -14,7 +13,6 @@ import { GanttContentMoveAction } from "../Gantt/gantt-content";
 export type BarProps = {
   task: BarTask;
   arrowIndent: number;
-  onDoubleClick?: (task: Task) => any;
   isProgressChangeable: boolean;
   isDateChangeable: boolean;
   isDelete: boolean;
@@ -28,7 +26,6 @@ export type BarProps = {
 export const Bar: React.FC<BarProps> = ({
   task,
   arrowIndent,
-  onDoubleClick,
   isProgressChangeable,
   isDateChangeable,
   onEventStart,
@@ -46,8 +43,8 @@ export const Bar: React.FC<BarProps> = ({
   return (
     <g
       className={styles.barWrapper}
-      onDoubleClick={() => {
-        !!onDoubleClick && onDoubleClick(task);
+      onDoubleClick={e => {
+        onEventStart(e, "dblclick", task);
       }}
       tabIndex={0}
       onKeyDown={e => {
diff --git a/src/components/Gantt/gantt-content.tsx b/src/components/Gantt/gantt-content.tsx
index 73c7a8e..2eaed0e 100644
--- a/src/components/Gantt/gantt-content.tsx
+++ b/src/components/Gantt/gantt-content.tsx
@@ -15,6 +15,7 @@ export type GanttContentMoveAction =
   | "mouseenter"
   | "mouseleave"
   | "delete"
+  | "dblclick"
   | BarMoveAction;
 export type BarEvent = {
   selectedTask?: BarTask;
@@ -44,14 +45,15 @@ export type GanttContentProps = {
     fontSize: string,
     fontFamily: string
   ) => JSX.Element;
+  onTasksDateChange: (tasks: Task[]) => void;
 } & EventOption;
 
 export const GanttContent: React.FC<GanttContentProps> = ({
   tasks,
+  dates,
   rowHeight,
   barCornerRadius,
   columnWidth,
-  dates,
   barFill,
   barProgressColor,
   barProgressSelectedColor,
@@ -59,12 +61,13 @@ export const GanttContent: React.FC<GanttContentProps> = ({
   barBackgroundSelectedColor,
   headerHeight,
   handleWidth,
-  arrowColor,
   timeStep,
+  svg,
+  arrowColor,
+  arrowIndent,
   fontFamily,
   fontSize,
-  arrowIndent,
-  svg,
+  onTasksDateChange,
   onDateChange,
   onProgressChange,
   onDoubleClick,
@@ -79,6 +82,7 @@ export const GanttContent: React.FC<GanttContentProps> = ({
   const [xStep, setXStep] = useState(0);
   const [initEventX1Delta, setInitEventX1Delta] = useState(0);
   const [isMoving, setIsMoving] = useState(false);
+
   // create xStep
   useEffect(() => {
     const dateDelta =
@@ -94,21 +98,13 @@ export const GanttContent: React.FC<GanttContentProps> = ({
 
   // generate tasks
   useEffect(() => {
-    const dateDelta =
-      dates[1].getTime() -
-      dates[0].getTime() -
-      dates[1].getTimezoneOffset() * 60 * 1000 +
-      dates[0].getTimezoneOffset() * 60 * 1000;
-    const taskHeight = (rowHeight * barFill) / 100;
-
     setBarTasks(
       convertToBarTasks(
         tasks,
         dates,
-        dateDelta,
         columnWidth,
         rowHeight,
-        taskHeight,
+        barFill,
         headerHeight,
         barCornerRadius,
         handleWidth,
@@ -136,14 +132,20 @@ export const GanttContent: React.FC<GanttContentProps> = ({
   /**
    * Method is Start point of task change
    */
-  const handleBarEventStart = (
+  const handleBarEventStart = async (
     event: React.MouseEvent | React.KeyboardEvent,
     action: GanttContentMoveAction,
     selectedTask: BarTask
   ) => {
     if (isKeyboardEvent(event)) {
       if (action === "delete") {
-        setBarTasks(barTasks.filter(t => t.id !== barEvent.selectedTask?.id));
+        if (onTaskDelete) {
+          await onTaskDelete(selectedTask);
+          const newTasks = barTasks.filter(
+            t => t.id !== barEvent.selectedTask?.id
+          );
+          onTasksDateChange(newTasks);
+        }
       }
     } else if (action === "mouseenter") {
       if (!barEvent.action) {
@@ -161,6 +163,8 @@ export const GanttContent: React.FC<GanttContentProps> = ({
       );
       setInitEventX1Delta(cursor.x - selectedTask.x1);
       setBarEvent({ action, selectedTask });
+    } else if (action === "dblclick") {
+      !!onDoubleClick && onDoubleClick(selectedTask);
     } else {
       setBarEvent({
         action,
@@ -217,9 +221,13 @@ export const GanttContent: React.FC<GanttContentProps> = ({
         (action === "move" || action === "end" || action === "start") &&
         onDateChange
       ) {
-        onDateChange(changedTask);
+        await onDateChange(changedTask);
+        const newTasks = barTasks.map(t =>
+          t.id === changedTask.id ? changedTask : t
+        );
+        onTasksDateChange(newTasks);
       } else if (onProgressChange) {
-        onProgressChange(changedTask);
+        await onProgressChange(changedTask);
       }
       svg.current.removeEventListener("mousemove", handleMouseMove);
       svg.current.removeEventListener("mouseup", handleMouseUp);
@@ -275,7 +283,6 @@ export const GanttContent: React.FC<GanttContentProps> = ({
               task={task}
               arrowIndent={arrowIndent}
               isProgressChangeable={!!onProgressChange && !task.isDisabled}
-              onDoubleClick={onDoubleClick}
               isDateChangeable={!!onDateChange && !task.isDisabled}
               isDelete={!!onTaskDelete && !task.isDisabled}
               onEventStart={handleBarEventStart}
diff --git a/src/components/Gantt/gantt.tsx b/src/components/Gantt/gantt.tsx
index 9b065d7..9e3990c 100644
--- a/src/components/Gantt/gantt.tsx
+++ b/src/components/Gantt/gantt.tsx
@@ -1,5 +1,5 @@
-import React, { useRef } from "react";
-import { ViewMode, GanttProps } from "../../types/public-types";
+import React, { useRef, useState } from "react";
+import { ViewMode, GanttProps, Task } from "../../types/public-types";
 import { Grid, GridProps } from "../Grid/grid";
 import { Calendar, CalendarProps } from "../Calendar/calendar";
 import { GanttContent, GanttContentProps } from "./gantt-content";
@@ -31,14 +31,19 @@ export const Gantt: React.SFC<GanttProps> = ({
   onTaskDelete,
   getTooltipContent,
 }) => {
-  const [startDate, endDate] = ganttDateRange(tasks, viewMode);
-  const dates = seedDates(startDate, endDate, viewMode);
   const svg = useRef<SVGSVGElement>(null);
+  const [ganttTasks, setGanttTasks] = useState<Task[]>(tasks);
+  const [startDate, endDate] = ganttDateRange(ganttTasks, viewMode);
+  const dates = seedDates(startDate, endDate, viewMode);
+
+  const handleOnTasksChange = (tasks: Task[]) => {
+    setGanttTasks(tasks);
+  };
 
   const gridProps: GridProps = {
     columnWidth,
     gridWidth: dates.length * columnWidth,
-    tasks,
+    tasks: ganttTasks,
     rowHeight,
     headerHeight,
     dates,
@@ -54,7 +59,7 @@ export const Gantt: React.SFC<GanttProps> = ({
     fontSize,
   };
   const barProps: GanttContentProps = {
-    tasks,
+    tasks: ganttTasks,
     rowHeight,
     barCornerRadius,
     columnWidth,
@@ -66,12 +71,13 @@ export const Gantt: React.SFC<GanttProps> = ({
     barBackgroundSelectedColor,
     headerHeight,
     handleWidth,
-    timeStep,
     arrowColor,
+    timeStep,
     fontFamily,
     fontSize,
     arrowIndent,
     svg,
+    onTasksDateChange: handleOnTasksChange,
     onDateChange,
     onProgressChange,
     onDoubleClick,
diff --git a/src/helpers/bar-helper.ts b/src/helpers/bar-helper.ts
index e1bc2ee..125d4e7 100644
--- a/src/helpers/bar-helper.ts
+++ b/src/helpers/bar-helper.ts
@@ -4,10 +4,9 @@ import { BarTask } from "../types/bar-task";
 export const convertToBarTasks = (
   tasks: Task[],
   dates: Date[],
-  dateDelta: number,
   columnWidth: number,
   rowHeight: number,
-  taskHeight: number,
+  barFill: number,
   headerHeight: number,
   barCornerRadius: number,
   handleWidth: number,
@@ -16,6 +15,13 @@ export const convertToBarTasks = (
   barBackgroundColor: string,
   barBackgroundSelectedColor: string
 ) => {
+  const dateDelta =
+    dates[1].getTime() -
+    dates[0].getTime() -
+    dates[1].getTimezoneOffset() * 60 * 1000 +
+    dates[0].getTimezoneOffset() * 60 * 1000;
+  const taskHeight = (rowHeight * barFill) / 100;
+
   let barTasks = tasks.map((t, i) => {
     return convertToBarTask(
       t,
@@ -35,6 +41,7 @@ export const convertToBarTasks = (
     );
   });
 
+  // set dependencies
   barTasks = barTasks.map((task, i) => {
     const dependencies = task.dependencies || [];
     for (let j = 0; j < dependencies.length; j++) {
diff --git a/src/helpers/other-helper.ts b/src/helpers/other-helper.ts
index 36d226e..2f27bf5 100644
--- a/src/helpers/other-helper.ts
+++ b/src/helpers/other-helper.ts
@@ -1,5 +1,12 @@
+import { BarTask } from "../types/bar-task";
+import { Task } from "../types/public-types";
+
 export function isKeyboardEvent(
   event: React.MouseEvent | React.KeyboardEvent
 ): event is React.KeyboardEvent {
   return (event as React.KeyboardEvent).key !== undefined;
 }
+
+export function isBarTask(task: Task | BarTask): task is BarTask {
+  return (task as BarTask).x1 !== undefined;
+}
diff --git a/src/types/public-types.ts b/src/types/public-types.ts
index 27ac75e..424e133 100644
--- a/src/types/public-types.ts
+++ b/src/types/public-types.ts
@@ -30,7 +30,7 @@ export interface EventOption {
    * Time step value for date changes.
    */
   timeStep?: number;
-  onDoubleClick?: (task: Task) => any;
+  onDoubleClick?: (task: Task) => void;
   onDateChange?: (task: Task) => void | Promise<any>;
   onProgressChange?: (task: Task) => void | Promise<any>;
   onTaskDelete?: (task: Task) => void | Promise<any>;