[Revised May 05].
For some commonly used functions, there is a 'shortcut key' which will lead directly into it without having to go through a pull down menu.
E.g. Pull down the top-bar choice, 'Window' . Observe that one of the choices is "Inventory F4". The "F4" indicates that there is a shortcut... pressing the <F4> key from the Main screen will jump directly into Inventory without having to select 'Window' at all.
Of course, you can still continue to use Window, then cursor down and select this item then <enter> OR press "I", but the shortcuts are convenient for commonly used functions once you know them.
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