Exception using HorizontalSplitPanel

[nim...@gmail.com]

Hi! I try to use HorizontalSplitPanel from GWT 1.4 RC but when calling
it's constructor I have such error in GWT Development Shell:

[ERROR] Uncaught exception escaped
com.google.gwt.core.client.JavaScriptException: JavaScript Error
exception: Invalid class string

at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:
481)
at
com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid(ModuleSpace.java:
270)
at
com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid(JavaScriptHost.java:
137)
at com.google.gwt.user.client.ui.HorizontalSplitPanel
$ImplIE6.addWidthExpression(HorizontalSplitPanel.java:134)
at com.google.gwt.user.client.ui.HorizontalSplitPanel
$ImplIE6.init(HorizontalSplitPanel.java:145)
at
com.google.gwt.user.client.ui.HorizontalSplitPanel.<init>(HorizontalSplitPanel.java:
270)
at com.google.gwt.sample.kitchensink.client.Panels.<init>(Panels.java:
135)
at com.google.gwt.sample.kitchensink.client.Panels
$1.createInstance(Panels.java:49)
at com.google.gwt.sample.kitchensink.client.Sink
$SinkInfo.getInstance(Sink.java:64)
at
com.google.gwt.sample.kitchensink.client.KitchenSink.show(KitchenSink.java:
93)

This error was obtained from KitchenSink example if run it from
eclipse in Hosted mode, but web-mode (i.e. using KitchenSink-
compile.cmd) works ok. Does anybody know how to solve the problem?