Thanks for the comment!
Try the following:
- Edit the "VolumeDown" hotkey (Win-K, then select "VolumeDown" and press Enter).
- Put the focus in the "Or press hotkey here:" textbox (Alt-H).
- Press (or turn) your volume down media key.
What do you see appear in the textbox? I do depend on the media controls to act as a keyboard key, and return a keyboard virtual key value, though I don't depend on the "VolumeDown" value explicitly.
I have a Dell Inspiron 6400, and the front volume controls (mute, volume down and volume up) respectively trigger the "VolumeMute", "VolumeDown" and "VolumeUp" keyboard values correctly. Maybe there is some special Dell software enabling this? I have "Dell QuickSet" installed by default. It does enable "Function-PageUp", "Function-PageDown" and "Function-End" to act has volume controls, and they do trigger the keyboard values and make the slimVOLUME bar appear.