How to get to a catalog name quickly

[webmasterpdx]

I like the programming tools on the prime as they are efficient using the menus, but sometimes a function name may not be in the menu or only in the catalog.
Now, first I gotta say, using the menu is way faster than trying to type the function name, which is what is so nice about the prime menu system.
I can get quickly to the area in the catalog usually by typing the first letter once the catalog menu is up. E.g. Lets say I want to get to purge, so I just type alpha p, and it'll usually get me to the start of the p functions and it's just a quick scroll and tap and I've got the purge function on the screen.
HOWEVER, typing the first letter doesn't often work....like I may have to type shift alpha p or exit the toolbox and enter it again and try again. Sometimes, i can't get it to go to the letter I want at all. There doesnt' seem to be a hard and fast rule on how to get it to always work.
Is there some trick I dont' know about to get this to work reliably?
Thanks in advance
-Donald