GTK has a nice feature allowing one to a press a function key while
selecting an item from the menus, which binds the selected function to that
key permanently (stores it somewhere in the filesystem).  I've used this
feature in Gnucash 1.6 to bind the `Actions/Split transaction' menu item
(in the Register window) to a function key.

One thing is that upon upgrade to 1.8.4, this binding has been forgotten. 
The problem is that even if I make this binding again, it only lasts until
the window in question is closed, and new windows do not have it.