Just copy the template from EQUI_Templates.xml and create your own custom WDT. That's what I did with my group window and it's not as hard as you might think. Having your own templates in your files makes them much more portable, and helps prevent anything breaking with patches.
You won't see it in the screenshot, but if you download my group window and have a look you'll see that the cursors are slightly smaller, there's no band in the middle obscuring them, and I also changed the colour slightly. Feel free to help yourself to any of the code or graphics:
http://www.eqinterface.com/download....php?s=&id=5745
Regarding the size of the buttons, EQ bases the initial size on the size of your graphics, but also scales them down automatically as you shrink your control (on the vertical axis).
What I'm now doing with any custom graphics like this is forcing myself to follow a naming convention so it's easy to find the right files & pieces. My filenames are now following this format:
EQUI_GroupWindow.xml
EQUI_GroupWindow_Myxiplx_Background.tga
Which makes it really easy to find all the required files for any one piece.
Then within the xml for each item, anything I modify gets prefixed with my name, and it's location, something like this:
Myx_Group_Background
Myx_Player_XP_Gauge
WDT_Myx_Target_TinyScroll
If you do that, it makes it really easy to move pieces from one piece to another - just doing a search replace to change "Myx_Group" to "Myx_Player" is enough to copy pieces without any name clashes, and without affecting any standard parts.