This is an applet to bring Lubuntu the option to have a menu for all apps located inside a panel (like Unity interface). This applet only works for GTK2 / GTK3 apps, and some Qt apps, LibreOffice and Firefox may fail loading it, and this applet is only available from Xenial Xerus 16.04 version.
First step: install the necessary packages. Open a terminal and paste this command:
sudo apt install xfce4-topmenu-plugin libtopmenu-client-gtk2-0 libtopmenu-server-gtk2-0 libtopmenu-client-gtk3-0 libtopmenu-server-gtk3-0 topmenu-gtk2 topmenu-gtk3
Second step: we need to edit a file:
…and put this content on it:
Now just save the file and reboot your system.
Third step: to add Topmenu to the LXDE panel, right click the panel, select “Add / Remove Panel Items”, click “Add” and select TopMenu:):
Now you can add more applets (like the app button or any other) next to your new menu. That’s all. Have fun!