Thanh,
If you are searching layers that are visible in the flexviewer map, this is how I handle that.
in the eSearchWidget.xml I set this: <popupsdisabled>true</popupsdisabled>
That way, you will not get the popup when clicking on the results table or grid, it will, however, zoom you to the clicked feature.
Then, I configure a popup in the config.xml for that layer. that way, any time you click on the feature, you will get the popup that honors the fields/formatting in the popupconfig.xml file.
I figure since the table/grid is giving me "most" the info, I don't need it to automatically popup a window with the same info. However, the popupconfig file lets you configure whatever info you want displayed, and only displays on click.
R_