It's certainly no solution - but just to add to the conversation: by default hitting command+(Show All Windows) shows the desktop. i.e. hitting command-F3 where F3 is functioning as a special key and not truly as "F3" If nothing else, it's an easy reach on the keyboard and somewhat logical. I still can't understand why there is no show desktop special key - especially in light of the dedicated dashboard key (who uses that?) and an empty space at F5.
I think that your problem is the "reverse" Fn key.
I think your problem can be described as:
"When I press F5 with my browser open, "Windows" does "something" and when I press Fn+F5, my browser reloads the page as I would expect".
This has nothing to do with Windows 8. Unfortunately there are many laptop suppliers (e.g. HP and Compaq) who do/did the same. I always had to go back to the BIOS to reverse (normalize) the Fn key function, so that F1 ... F12 worked without first pressing Fn and that the "special" functions like volume, WiFi, Screen Switching, etc. all require the use of the Fn key first.
From the Lenovo Manual. Change settings in your BIOS!
Setting hotkey mode
By default, the hotkey functions are accessible by pressing the appropriate
hotkey. However, you can disable the hotkey mode in the BIOS setup utility.
To disable the hotkey mode:
1 Restart the computer.
When the Lenovo logo appears, immediately press
Fn+F2 to enter the BIOS setup utility.
2 In the BIOS setup utility, open the Configuration menu, and change the
setting of HotKey Switch from Hotkey Mode to Legacy Mode.
3 Open the Exit menu, and select Exit Saving Changes.
Note: When hotkey mode is disabled, press the Fn key and the appropriate hotkey to access the corresponding hotkey function.
Not in the manual:
From now on you enter the BIOS most likely with just F2.
Best Answer
Fn is not a real key that OSes recognize, since it doesn't produce a scan code (except on Mac keyboards). The keyboard controller sends the real scan code if you press Fn along with some other keys. Therefore if there's no physical Fn-lock key on your keyboard (which probably doesn't, as some one commented) you'll need to remap those keys on software
If you have root permissions there are various solutions to remap
/system/usr/keylayout/Generic.kllayout file and copy it to/system/usr/keylayoutIf you have a non-rooted device then you can use External Keyboard Helper. Just remap the scancode for Home to F1 and vice versa. Similarly for other keys. You can see the remap tutorial that shows you how to get Esc without Fn like in your keyboard
For more information you can read