Fix returned `percent` when clicking the `Scrollbar` `track`

data/core/scrollbar.lua

@@ -189,8 +189,9 @@ function Scrollbar:_on_mouse_pressed_normal(button, x, y, clicks)
       self.drag_start_offset = along - y
       return true
     elseif overlaps == "track" then
+      local nr = self.normal_rect
       self.drag_start_offset = - along_size / 2
-      return (y - self.normal_rect.along - along_size / 2) / self.normal_rect.along_size
+      return common.clamp((y - nr.along - along_size / 2) / (nr.along_size - along_size), 0, 1)
     end
   end
 end