Sad reality: it is not possible. Mintmenu sorts alpabetically, so it's Asunder/Banshee/Caja/dconf-Editor
An uncomfortable but possible way would be to rename all the entries to something like 11-Caja/14-dconf-Editor/34-Banshee/78-Asunder. After a restart you should have the entries in a new order.
An easier way is the "classical" way: instead of using mintmenu just put the programs you use most frequently as icons on your desktop.
Tower: Sparky 64 bit Mate+mintmenu - Netbook: LMDE 2 Mate 32bit