How can zimlets be localized? I need localized texts for e.g. "<toolTipText>" in <zimlet_name>.xml.

The "Zimbra Zimlet Whitepaper.pdf" mentions localization, but doesn't give any useful examples. Google was of no help either!

I have tried the following in <zimlet_name>.xml:

<zimletPanelItem label="${msg.titel}" icon="Security-panelIcon">
and add a <zimlet_name>.properties file to the <zimlet_name> zimlet, with the following content:

tooltip = "My localized tooltip"
titel = "My localized title"
Obvioulsy I'm doing something wrong, because this doesn't work.

Could someone show how to accomplish the above?