in what situation GWT will generate the CSS class name in random?

[wahaha]

in what situation GWT will generate the CSS class name in random?

and in what situation it will remain the original name?

for example:
1. use {style.xx} in ui.xml
2. use {xx} in ui.xml
3. use widget.setStyleClassName() in java code

[Thomas Broyer]

CSS class name obfuscation only happen in CssResource; and a <ui:style> in a UiBinder template is a form of CssResource.

So only case "1" in your list would use an obfuscated class name, because 'style' references (by default) a <ui:style>, i.e. a CssResource; {xx} would use the value of xx (any @UiField named 'xx' in your class, and/or anything with a field="xx" in your ui.xml), and setStyleName uses the argument give verbatim.

[wahaha]

does this will affect:

"@external .t-label" in ui.xml