You can assign keys as shortcuts to buttons and controls (referred to as "commands") used in all windows. These are called "hotkeys", and your assignment is typically user-specific. Each window has its own set of commands which can be assigned to hotkeys. If a keypress in a window is not a hotkey for a command in that window, it gets passed up to the Main window for matching.
Note that the “Variables Control” handles hotkeys differently than other windows. The following key presses are not passed up to the Main window if they are not assigned to a command in the Variable window.
Not sending these hotkeys up to the Main window prevents Analyst from interfering with the typing of content into the Variables control.