build number:2.6.0.v20100517-0630

steps to reproduce:
1. deploy birt.
2. preview a report in frameset servelet and add__rtl=true in url

expected result:
viewer navigation and toolbar aligned from right to left

actual result:
it keep displays from left to right
works for me. please check if the url contains duplicate __rtl parameter.
maybe caused by uncleared cache, close it.