✨ Middle clicking blank space in vertical tabs works

See suggestion in #137

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## 1.0.0-a.77
 
+### Feature
+
+- Vertical tabs: Open new tab w/ clipboard contents on space middle click
+
 ### Fixed
 
 - Pinned vertical tabs are no longer positioned. Sorta defeats their purpose, but it stops a semi-major bug

src/browser/base/content/browser-verticaltabs.js

@@ -114,6 +114,12 @@ var VerticalTabs = {
       this.enableVerticalTabs()
     }
 
+    // Cause middle click to open a new tab
+    this.arrowScrollbox?.addEventListener('click', (event) => {
+      if (event.button != 1 || event.target != this.arrowScrollbox) return
+      gBrowser.handleNewTabMiddleClick(this.arrowScrollbox, event)
+    })
+
     this._initialized = true
   },