What defines Z-index?
 

What defines Z-index of items? part of new modification i'm making consists of
4 layers i add ontop of another


I'm using photoshop DDS plugin (the save thing) What is the proper save format
for the images - are there any documentation about it (preferable specifically for EQ2)

UI items higher up in the code are on top. Containers are rendered below their sub-components. For example the folowwing object tree...

PageA
|-ObjectA1
|-ObjectA2
|-PageB
| |-ObjectB1
| L-ObjectB2
L-ObjectA3
PageC

Would render..
PageC on the bottom.
PageA next
ObjectA3
PageB
ObjectB2
ObjectB1
ObjectA2
ObjectA1

As far as DDS guides go, only ones I know of are on the INVIDIA site. Not much to know really, the save dialog box tells you all you need to know about the various formats.

More bits = better qaulity and larger file size.

MIPs are smaller versions of the original image included in the file to speed render times when the image is shrunk. The trade off is larger file sizes, which eats up RAM.

JPEG compression sacrifices image quality for smaller file sizes.