[Chiba-users] Getting error message for submit-error event

[Andriy V. <And...@gm...>]

How can i display error message from unsuccessful submit response, using 
common chiba/xforms techniques.
I have several possible bad-case scenarios, and it would be nice to show 
exact error messages.
Something like this would be appreciated:
<xf:model>
    <xf:message level="ephemeral" ev:event="xforms-submit-error">Submit 
failed ($reason)</xf:message>
</xf:model>

of course i can do something like:

<xf:message level="ephemeral" ev:event="xforms-submit-error" 
bind="submit-error-message" />

but in this case i should always deliver valid response, and this will 
affect form state.

The best would be presence of something like 
/xforms/XFormsServlet?getLastSessionError. In that case i can do following:
    <xf:message level="ephemeral" ev:event="xforms-submit-error" 
src="/xforms/XFormsServlet?getLastSessionError" />

So how it can be done ?