diff --git a/example/src/index.js b/example/src/index.js
index 3231ea4..e23eb83 100644
--- a/example/src/index.js
+++ b/example/src/index.js
@@ -70,4 +70,4 @@ const initExample = (rootElement = document.getElementById('root')) => ReactDOM.
   rootElement
 )
 
-export { initExample }
+export { initExample }
\ No newline at end of file
diff --git a/src/Rect/index.js b/src/Rect/index.js
index e8e34ca..b1537f2 100644
--- a/src/Rect/index.js
+++ b/src/Rect/index.js
@@ -14,6 +14,8 @@ const zoomableMap = {
   'sw': 'bl'
 }
 
+const MAIN_BUTTON = 0;
+
 export default class Rect extends PureComponent {
   static propTypes = {
     styles: PropTypes.object,
@@ -35,6 +37,7 @@ export default class Rect extends PureComponent {
 
   // Drag
   startDrag = (e) => {
+    if (e.button !== MAIN_BUTTON) return
     let { clientX: startX, clientY: startY } = e
     this.props.onDragStart && this.props.onDragStart()
     this._isMouseDown = true
@@ -61,7 +64,7 @@ export default class Rect extends PureComponent {
 
   // Rotate
   startRotate = (e) => {
-    if (e.button !== 0) return
+    if (e.button !== MAIN_BUTTON) return
     const { clientX, clientY } = e
     const { styles: { transform: { rotateAngle: startAngle } } } = this.props
     const rect = this.$element.getBoundingClientRect()
@@ -99,7 +102,7 @@ export default class Rect extends PureComponent {
 
   // Resize
   startResize = (e, cursor) => {
-    if (e.button !== 0) return
+    if (e.button !== MAIN_BUTTON) return
     document.body.style.cursor = cursor
     const { styles: { position: { centerX, centerY }, size: { width, height }, transform: { rotateAngle } } } = this.props
     const { clientX: startX, clientY: startY } = e