I have an Undecorated JFrame with a JCheckbox added to it. On clicking the checkbox, I make the JFrame transparent. When I do this on Vista, I see the label of the checkbox becoming bold & blurred. Looks as if the antialias is removed. Looks a bit odd.
I reproduced it on WinVista Home Premium with Aero enabled, using jdk6u10-b27. This machine is installed with ATI Radeon X1600 and a LCD monitor. Reproducible independent of look and feels. I could not reproduce this on WinXP.
I have attached a sample test and the screenshots (before and after making the window transparent).