The symbology system has been upgraded. All symbology options are now available through the user interface, including label symbols, transparency, and scale thresholding. New symbol types include gradient paint and texture paint.
A new theme type is available to symbolize dither patterns based on the relative values of multiple attribute columns. This type of theme is useful to show changes in composition over time (e.g. species, cover type, seral stage).
MrSid images have an option to assign a color that should be treated as transparent.