I get around it by using the bottom part of the main image as a separate image for the bottom panel. In other words, if I'm starting with an image of 1600x1200, I split it into 2 images - one of say 1600x1125 and another of 1600x75. Then I use the large one as the Bitmap100 (primary image) and the small bottom section for the Bitmap200 (bottom panel).

If you're picky like I am it takes a little tweaking to make it appear seamless but it works. Also, I think the "stretching" might not be consistent throughout various resolutions; i.e., a screen that I've made that looks good on the 1600x1200 resolution might be off a little bit at 1280x1024. Another quirk is that in my example of a 75 pixel tall bottom image, the bottom panel height is set for 70, but I had to use a 75 pixel high image to make it match up.

Anyway you get the idea. The end result is the appearance of a single full screen image and the "shutdown" button lies on top of it in the lower left.

Have you tried double-clicking them? Or maybe you need to import them, if they're in .exe format.