You should follow this how-to if you want to either:
- Replace the default Content tab of a folderish document type
 - Or add a new tab from which users should be able to create children documents.
 
To do so, you basically need to create a new tab with some specific properties.
Before You Start
Before you follow the steps below, you should already have configured the items below:
- In the Settings > Application Definition menu, make sure the target package Nuxeo JSF UI is checked.
 - A document type with the following properties:
- Folderish facet
 - Accepts children document types (File or extending file)
 
 - A content view, obviously.
 
Setting up Your Custom Tab
To set a content view with Drag&Drop and the New button:
- In Studio, go to Listings & Views > Tabs.
 - Click the New button and enter a name for the Feature ID: 
ContentViewWithDnDandNewButton. And click Next to validate. - Set a value for Order if you don't want the new tab to be displayed as the first tab.
 - Drag the widget Drop zone from Featured widgets > Built-in widgets and drop it in the first cell of the tab grid.
 In the Widget Layout Editor that pops up, set the properties as follow:
- Hide label: checked
 - Add surrounding form: unchecked
 - Custom configuration properties: 
dropContext:ContentView 
- Click on Save.
 - Click on the icon 
 of the Drop zone widget. - In the first line, drop a Generic widget from More widgets > Advanced widgets.
 In the Widget Layout Editor, set the properties as follow:
- Hide label: checked
 - Widget type: documentActionsWithForms
 - Category: Folder Toolbar
 - Actions Display: Buttons
 - Overall display: Horizontal bloc
 
- Click on Save.
 - In the second line, drop a Content View widget from Featured widgets > Tab widgets.
 In the Widget Layout Editor, set the properties as follow:
- Content View name: Select the content view you want to display.
 
- Click on Save.
 - Cick on Go back to previous page to go back on the tab definition screen.
 - Go to your tab's Activation tab and set the conditions (permissions, document types, etc) to make the new tab visible. Save.
 
Now you just need to hot-reload your Studio project. And a new tab will be visible for the selected document types.
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