stop screen share button added

src/App.vue

@@ -1,7 +1,8 @@
 <template>
   <v-app>
     <v-content>
-      <v-text-field  v-if="!start" v-model="username" label="please enter name"></v-text-field> <v-btn v-if="!start" @click="startM">Start</v-btn>
+      <v-text-field  v-if="!start" v-model="username" label="please enter name"></v-text-field> 
+      <v-btn v-if="!start" @click="startM">Start</v-btn>
       <VueJanus v-if="start" server="https://vid.w3ic.org/janus" :room="room" :username="username"/>
     </v-content>
   </v-app>

src/lib/VueJanus.vue

@@ -2,7 +2,7 @@
     <v-container>
         <v-btn @click="deviceSelectDialog = true">change</v-btn>
         <v-btn @click="screenShare">share a screen</v-btn>
-
+        <v-btn @click="screenShareStop" v-if="screenShareStarted">stop screen share</v-btn>
 
         <v-dialog
                 v-model="mozillaAlert"
@@ -129,7 +129,8 @@
                 deviceSelectDialog: false,
                 noVid: false,
                 shareScreenId: null,
-                remoteStreams: []
+                remoteStreams: [],
+                screenShareStarted: false
             }
         },
         name: "VueJanus",
@@ -196,7 +197,14 @@
                         onlocalstream: this.onlocalstreamScreen
                     }
                 )
-
+                this.screenShareStarted=true;
+            },
+            screenShareStop(){
+                let srcObject=this.$refs.ownstreamscreen.srcObject;
+                for (const track of srcObject.getTracks()) {
+                    track.stop();
+                }
+                this.screenShareStarted=false;
             },
             screenShare () {
                 if(!this.$janus.isExtensionEnabled()) {