Description:
Steps to reproduce:
 - close all output windows and close IDE (or close IDE and delete user dir)
 - restart the IDE
 - create a BPEL process
 - switch to sources
 - press the Validate XML button. 
The output window will be opened but nothing will be displayed there

Evaluation:
I tried the simple case of just closing all the output windows and shutting down
studio and reoponing studio. There did not seem to be any problem. The
validation output window appeared the first time I clicked on the validate button. 

Maybe in QE case, the IDE was just very busy when the button was pressed
following restart? If you opened TRS process perhaps CPU was consumed by diagram
building and therfore, the first press on the Validate was not processed quickly
and you pressed button a second time. Please check to see if this might be case
by observing CPU activity.