I am having the same problem trying to set a background image
on my tab style.
I also noticed, tabStyleName="tabStyle" and
selectedTabTextStyleName="selectedTab" both work, however
firstTabStyleName="firstTab" and lastTabStyleName="firstTab" don't
seem to have any kind of effect on the tabs.
I tried using background-image: Embed(image.png); and
backgroundImage: Embed(image.png) as well as url()s but nothing
worked. Has anyone had success applying a background image to Tab
Navigator tabs or is this style attribute not working?