showClickMask - attempting to remove invalid object :null from tab order

[test]

Using SmartGWT 2.2, latest GWT SDK, happens on all major browsers.

I'm wondering, if anyone can tell me under what circumstances "MUP2:WARN:clickMask:showClickMask - attempting to remove invalid object :null from tab order" warning appears?

I get 20 of them (in dev. mode) within a second when calling "listGrid.fetchData(getFilterCriteria());" and I'd like to take care of them, if possible.

getFilterCriteria():

	private Criteria getFilterCriteria() {
		final Criteria crit = filterDF.getValuesAsCriteria();
		
		if(crit.getAttributeAsObject("vesselNameFilter") == null)
			crit.addCriteria("vesselNameFilter", "*");

		if(crit.getAttributeAsObject("messageFilter") == null)
			crit.addCriteria("messageFilter", "*");

		return crit;
	}

Warning:

13:22:10.292 [ERROR] [MBT] 13:22:10.297:MUP2:WARN:clickMask:showClickMask - attempting to remove invalid object :null from tab order
com.smartgwt.client.core.JsObject$SGWT_WARN: 13:22:10.297:MUP2:WARN:clickMask:showClickMask - attempting to remove invalid object :null from tab order
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:105)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
    at com.google.gwt.dev.shell.BrowserChannel.reactToMessagesWhileWaitingForReturn(BrowserChannel.java:1714)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:165)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:120)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:507)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid(ModuleSpace.java:284)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid(JavaScriptHost.java:107)
    at com.smartgwt.client.widgets.grid.ListGrid.fetchData(ListGrid.java)
    at com.EMA.MBT2.client.windows.InboxWindow.onSearch(InboxWindow.java:643)
    at com.EMA.MBT2.client.windows.InboxWindow.setInboxDataSource(InboxWindow.java:597)
    at com.EMA.MBT2.client.windows.InboxWindow.<init>(InboxWindow.java:116)
    at com.EMA.MBT2.client.panels.TopPanel$8.onClick(TopPanel.java:128)
    at com.smartgwt.client.widgets.events.ClickEvent.dispatch(ClickEvent.java:96)
    at com.smartgwt.client.widgets.events.ClickEvent.dispatch(ClickEvent.java:1)
    at com.google.gwt.event.shared.HandlerManager$HandlerRegistry.fireEvent(HandlerManager.java:65)
    at com.google.gwt.event.shared.HandlerManager$HandlerRegistry.access$1(HandlerManager.java:53)
    at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:178)
    at com.smartgwt.client.widgets.BaseWidget.fireEvent(BaseWidget.java:67)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
    at com.google.gwt.dev.shell.BrowserChannel.reactToMessagesWhileWaitingForReturn(BrowserChannel.java:1714)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:165)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:120)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:507)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:264)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:188)
    at sun.reflect.GeneratedMethodAccessor88.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
    at com.google.gwt.dev.shell.BrowserChannel.reactToMessages(BrowserChannel.java:1669)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:401)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:222)
    at java.lang.Thread.run(Unknown Source)

[newbieGWT]

Hi,

Did you manage to work out the cause of the problem?

[test]

I have not. I hoped someone with more knowledge with inner-workings of SC could help me.