https://forums.opera.com/topic/48440/show-sidebar-option-in-context-menu-on-start-page
'Show sidebar' option in context menu on start page | Opera forums
Apr 13, 2021 - Add show sidebar option in the right click context menu on star page.
show sidebarin contextstart pageoption
https://gnome.pages.gitlab.gnome.org/libadwaita/doc/main/property.OverlaySplitView.show-sidebar.html
Adw.OverlaySplitView:show-sidebar
Reference for property Adw.OverlaySplitView:show-sidebar
adwshowsidebar