Yeah, this is definitely a bug, but we're having a difficult time tracking it down. There's something with 10.6.5 and .6 that is overriding our dialog sizing code.
I've attached an example of this (macsizetest.e). It's got a dialog with three buttons that will size the dialog based on what button you click. On 10.5.8, this dialog works fine and will size the dialog differently with each button click. However, on 10.6.5 and .6, clicking the buttons will make the dialog "flash" to the desired size and then snap back to the last user set size. This has to be the result of a change in X11 on 10.6.5, but I'm still not sure what it is.
I'm going to keep looking into this and I'll let you know when I figure out what's going on.
Scott