I did work for supporting RTL in GXT. I have a version which supports RTL almost in full however I have one small issue which I wasn't able to resolve. The following image will help me explain the problem.
On the right you see the good behavior of the combo box, opening under the field. On the left you see that the opened div is pushed to the left.
Here is what I got so far... Outside a "FormPanel" the combo worked fine in RTL. Within a "FormPanel", as long as the components added to the panel are "TextField" or "Combobox" everything is fine. When I add a different type of component like radio buttons, slider, text area or else it causes the combo to behave as it is on the left image. The calculation error occurs in El.java in the translatePoints method
for some reason o.x and l are not equal although they should be. I wasn't able to trace why adding one of the above described components to the panel causes this problem.
I used "CustomFormExample" which comes with GXT sample code as my test case class. Any help pointing me to the right direction will be appreciated.
BTW. I'll be happy to contribute my work on RTL, just drop me a note...
I managed to solve the issue. Things are working fine with firefox, however I have lots of problems with ie. It seems that whenever I use a RTL locale it reports a wrong offsetWidth. Do you know anything about that?