Open a Tab or Multiple Tabs
You can open a single tab simply by clicking the tab when the mouse changes to pointer. You can also select multiple tabs by clicking the right side of the tab (the cursor is in default mode), and there will be a toolbar showed below the navigation bar:
Now you can open the selected tabs by clicking the icon in the toolbar.
You can use ctrl and shift keys (macos will be command and shift) to select multiple tabs in a group or cross groups.
Delete One or Multiple Tabs
To delete a tab, move the mouse to the left of the tab, a close icon will be showed. Click it to delete the tab.
To delete multiple tabs, select them by clicking the right side of the tab, using ctrl and shift (macos will be command and shift) to select more than one tabs.There will be a toolbar showed below the navigation bar, click the delete icon to delete the selected tabs.
Drag Tabs within a Group or into Another Group
You can drag tabs within a group or into another group, and the order of tabs in the group will be remembered. Select the tab by clicking the right side of the tab (you can select one or more), then drag it to somewhere in this group or to another group.