Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
One of the pleasant problems with Linux Distros is the huge number of applications available. For Ubuntu Ultimate Edition (and others) there can be so many applications in a Kmenu section that it covers the entire desktop like this:
So, how to fix this? You want to make the Kmenu more organized using submenus. Just highlight an item in the section of Kmenu you want to change and right click. A menu will appear, just highlight the "Edit Item" option and left click. This will invoke the KDE Menu Editor:
Now use the Menu Editor to add a new submenu.