Steps to reproduce:

1. Type something
2. Select part of the text
3. Click Grow Text few times, click Shrink Text few times

Results:
Sometimes editor part loose focus(so next clicks on Shrink/Grow Text do nothing), sometimes clicking this buttons simply resets selection, sometimes selection is moved...

GXT version 2.0.1
web mode in Chrome
Chrome 2.0.172.39
Windows 7, 64bit (Windows Vista, 64bit)

Code:
public class Test implements EntryPoint {
  public void onModuleLoad() {    
     RootPanel.get().add(new HtmlEditor());
  }
}