The tab widgets display a set of tabs. Each tab can contain it’s own set of widgets.
Editing
When editing the tab widget a list of tabs is displayed. Use the properties panel to add a tab. Reorder tabs with the arrows beside the names. Edit the tab name and icon with the edit button 
beside the name.
To add widget or edit a tab, select it from the tab bar. Then use the green edit button in the top right 
.
Properties
Height - Adjust the height of the widget
Minimum width - Adjust the minimum width of the widget
Stack Tabs Vertically - By default the tab bar is horizontal across the top, select to switch to a vertical tab bar.
Position icon above text - By default an icon is placed to the left of the tab names, select to place it above. Only an options for horizontally stacked tabs.
Use Dark Theme - Select to switch to the dark theme.
Width of Sidebar - Adjust the sidebar width. Only an options for vertically stacked tabs.
Position of Sidebar - Choose to show the sidebar on the left right. Only an options for vertically stacked tabs.
Add Tab - Select to add a new tab to the group. Enter the tab name, choose an icon, then press Add in the pop up.