As far as I know, this is just the way Motorola designed their BLUR interface. See, for example, this screenshot from a blog post on Motorola's dev site:
This basically appears anywhere that a developer uses a
ListView object, which is fairly common as it's the native way to display...well, a list of things (appropriately named, no?). Motorola describes their reasoning as such:
The gray background at the bottom of the list is inherited from the device theme. Its purpose is to show users where the list ends.
In your case, the gray is instead white (which I've also seen on the Droid X), but the same concept applies.
If you want to get rid of it you basically need to re-theme your device and get rid of the BLUR UI, which is generally not possible without rooting and using a custom ROM due to how tightly integrated it is into the system. Alternatively, you could email the developer and politely ask them to re-theme the
ListView, since they have the option to explicitly override the default theming if they want. Whether or not they think it's worth the effort is kind of out of your control at that point, though.