The viewer's template files(the HTML, CSS and JS files) generate widgets based on the type of report parameters, which should be visible. You can override the default behavior and specify custom parameters editors, with customized behavior, which will suit your requirements.
Consider the example in the How To: Create a custom parameter editor article
. With the given example in the article, it is enough to substitute the name of the widget to
kendoMultiSelect to get the new parameter's editor in action.
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