Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Overriding Tabs Using a Standard List Controller

Pages that use standard list controllers can be used to override tabs. For example, if you create a page named overrideAccountTab that is associated with the Account standard list controller:
1<apex:page standardController="Account" recordSetVar="accounts" tabStyle="account">
2  <apex:pageBlock >
3    <apex:pageBlockTable value="{!accounts}" var="a">
4      <apex:column value="{!a.name}"/>
5    </apex:pageBlockTable>
6  </apex:pageBlock>
7</apex:page>
Then, you can override the Account tab to display that page instead of the standard Account home page.
  1. From the object management settings for accounts, go to Buttons, Links, and Actions.
  2. Click Edit for the Accounts Tab.
  3. From the Visualforce Page drop-down list, select the overrideAccountTab page.
  4. Click Save.

Make sure you have made this page available to all your users by setting the page level security appropriately.

Note