Unfortunately, it can't be implemented into the laptop mod yet because Minetest doesn't support image elements for everything, and it also doesn't have pressed or hover images for anything at all (See viewtopic.php?f=5&t=19485). Another problem is that the laptop mod doesn't have a forward button, only a back button. Once these are fixed, I'm going to give the laptop mod a huge overhaul in looks.
Here's a preview of the Undersea theme.
Spoiler
App Background (Hover and pressed buttons not shown)
Buttons (Major button and greyed out button not shown)
Checkboxes
Taskbar Buttons (In case they're ever needed)
Tabs
Dropdown
Slider (Like the sound volume)
Scrollbars