mouse interactive scrollbar.

lib/widget.js

@@ -4771,6 +4771,38 @@ function ScrollableBox(options) {
       }
       this.track.style = this.style.track;
     }
+    // Allow controlling of the scrollbar via the mouse:
+    this.on('mousedown', function(data) {
+      if (self._scrollingBar) {
+        // Do not allow dragging on the scrollbar:
+        delete self._drag;
+        return;
+      }
+      var x = data.x - self.aleft;
+      var y = data.y - self.atop;
+      if (x === self.width - self.iright - 1) {
+        // Do not allow dragging on the scrollbar:
+        delete self._drag;
+        var perc = (y - self.itop) / (self.height - self.iheight);
+        self.setScrollPerc(perc * 100 | 0);
+        self.screen.render();
+        var smd, smu;
+        self._scrollingBar = true;
+        self.screen.on('mousedown', smd = function(data) {
+          var y = data.y - self.atop;
+          var perc = y / self.height;
+          self.setScrollPerc(perc * 100 | 0);
+          self.screen.render();
+        });
+        // If mouseup occurs out of the window, no mouseup event fires, and
+        // scrollbar will drag again on mousedown until another mouseup occurs.
+        self.screen.on('mouseup', smu = function(data) {
+          self._scrollingBar = false;
+          self.screen.removeListener('mousedown', smd);
+          self.screen.removeListener('mouseup', smu);
+        });
+      }
+    });
   }
 
   if (options.mouse) {