I've verified some functionality after refraction of CSS dialog and found some probelms:
1) First of all, when we try to call a CSS dialog or CSS class wizard more then one time for the sane CSS file, CSS dialog is broken. But we think that is a bug of Eclipse 3.5 M7 or maybe something has changed in model itself, because where are no errors under Eclipse 3.5 M6.
Step to reproduce:
1) Open CSS file
2) Call CSS dialog
3) Close CSS dialog
4) Call CSS dialog again
RESULT: Exception occurred. but stack trace is unavailable.

2) Next situation is related to previous situation. It's reproducible starting from Eclipse 3.5 M7 version.
1) Call CSS class wizard
2) Choose CSS file
3) Enter new CSS style name
4) Press Next
ASSERT: You'll see new CSS style and it's properies (screenshot-2)
5) Press Back and then Next again
ASSERT: Another CSS style is created with the same name, that is not correct (screenshot-3)

3) Next small problem is connected to validation of properties fields, this is our bug:
1) Open CSS class wizard
2) And put ; into some field
ASSERT: Validation message is occurred, but Finish and Apply buttons are enabled (screenshot-1). Trying to reproduce this situation with CSS dialog (not wizard) leads to the correct result (OK and Apply buttons are disabled). All is OK.