fixed: permision dialog show state + screen share button state

src/lib/VueJanus.vue

@@ -280,7 +280,7 @@
             },
             onlocalstreamScreen (stream) {
                 if(this.screenShareStarted)
-                    this.screenShareStarted=false;
+                    this.screenShareStarted=true;
 
                 this.$refs.ownstreamscreen.srcObject = stream
             },
@@ -306,7 +306,9 @@
                         onlocalstream: this.onlocalstreamScreen
                     }
                 )
-                this.screenShareStarted=true;
+
+                this.mozillaAlert=false;
+                this.chromeAlert=false;
             },
             screenShareStop(){
                 var srcObject=this.$refs.ownstreamscreen.srcObject;
@@ -316,6 +318,8 @@
                 var unpublish = { request: 'unpublish' };
                 this.janusScreenShareHandle.send({ message: unpublish });
                 this.janusScreenShareHandle.detach();
+
+                this.screenShareStarted=false;
             },
             screenShare () {
                 if(!this.$janus.isExtensionEnabled()) {