The Accordion tab is a single-level tab stacking feature that can expand and collapse stacked tabs. The collapsed tab stack / Accordion tab is of the same width as a regular tab but with multiple tabs in it. It is useful for maximizing the screen real estate when there are too many tabs open.
Enabling Accordion tabs:
As this feature is available only from version 4.1 of Vivaldi, first check the version by typing in the address bar:
If the version is below 4.1, you would need to update to use this feature.
Once updated, access Vivaldi settings by typing in the address bar:
Open settings and click on Tabs.
Then scroll down to TAB FEATURES in the right pane and enable the option of Accordion.
Adding Accordion tabs:
After it is enabled, to add tabs as Accordion, select them by holding down the Ctrl key and left-clicking them.
Just as with the previous types of tab stacking, to add them right-click on the selected tabs outline and select Stack selected tabs.
It will add these tabs as Accordion and the tabs will be displayed differently from the other tabs by having an outline over them.
As the name suggests, like an Accordion these tabs will expand and collapse by clicking on the arrow next to them or double-clicking on the stack.
When collapsed, these tabs will be visible as a single Accordion tab with a number next to them that indicates the total tabs stacked. You can also add other regular tabs by dragging them over the Accordion tab.
Also, you can view these stacked tabs as a preview by hovering the mouse over the Accordion tab.
Removing Accordion tabs:
To remove all the tabs from the stack, right-click on the Accordion tab and choose Remove from Tab Stack.
Also, individual tabs that are a part of this can be removed or closed through the preview pop-up.
The tabs will now be visible as regular tabs.
Another advantage of Accordion tabs is creating multiple such tabs. So, you can stack different relevant tabs as a single Accordion tab.
This saves a lot of screen space as these tabs can expand only if you have to.