Collection of Useful GTK Settings
From ArchWiki
The purpose of this page is to collect GTK configuration settings which can e.g. be used within ~/.gtkrc-2.0.
Enabling Customizable Keyboard Shortcuts
You can customize your GTK applications' keyboard shortcuts (those are called accelerators in GTK terminology) by hovering your mouse over a menu item and pressing your desired key combination. However, this feature is disabled by default. To enable it, set
gtk-can-change-accels = 1
Speed up your Gnome menu
This setting controls the delay between you pointing the mouse at a menu and that menu opening in Gnome. Change this to a setting you prefer. I guess the number is in milliseconds, eg 250 being a quarter of a second.
gtk-menu-popup-delay = 0