Thank you for your suggestion. I am not sure if we should assume and hard-code the external links behavior on behalf of the application developer, though. From what I see, PhoneGap is also not sure what people expect to happen when a link with target="_blank" is clicked, hence the abundance of discussions (and solutions) available as google results.
If you discover that Kendo UI Mobile is somehow interfering with the suggested solutions (e.g. a solution works in a regular web page with links in it, but does not work with data-rel="external" links when a Kendo UI Mobile app is instantiated), please let us know. We will do our best to help.
All the best,
the Telerik team
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