[offtopic]I am thrilled I found this wonderfull app and I will recommend it to everyone I know who has windows 8.

[/offtopic]
I'm trying to open the menu with a custom image. So I selected this image:

As image size I left 0 and this is what shows:

on mouse over the viewport stays the same, but the image moves up so the cross in the above image is visible.
Is this because the menu expects an image with 2 states in 1 image, like used on websites when with CSS hover the top property of the image is changed?
And/or does the image have to be a specific size?
Please note I am using a double taskbar row. If I select the shell image, it works fine. If I slecet the Windows default image the background behind the image looks bad on mouseover (so thats why I want to use a custom image).
If I edit the image size in the menu-config to the height or width or bit-depth, the output is exactly the same.