fixed window toggling with multiple windows (fixes #619)

app/lib/index.ts

@@ -34,6 +34,7 @@ process.on('uncaughtException' as any, err => {
 })
 
 app.on('second-instance', (_event, argv, cwd) => {
+    application.presentAllWindows()
     application.send('host:second-instance', parseArgs(argv, cwd), cwd)
 })