On apps or reader view, click on the edit icon of the tab you want to share. If necessary, uncheck the "Library tab" option and then click on the share button.
If you wish to share multiple tabs, paste the URL you just copied into a text editor. Repeat this process for all tabs you wish to share so you have a URL for each.
Connect to the dashboard you wish to share the corpus tab(s) to.
Visit each of the URLs you copied and on the resulting page, check the "Select all" option and make sure you choose the master dashboard in the "Add to my dashboard" dropdown.
Feeds, tracked topics, analytics and custom apps are currently supported. Note that analytics can only be shared between copies of the same Premium Dashboard. Sharing between separate Premium Dashboards is only available on Netvibes For Enterprise with the Hierarchical Dashboards feature.