Open Files are a great new feature in Komodo 8.5. They were already introduced in 8.0 but have received some significant updates since then. This video walks you through the basics and explains the main purpose of the widget.
A great new feature we've added to Komodo 8.5 is code refactoring. You can rename elements without using a Find & Replace dialogue. For example, you can rename every instance of an element by right-clicking on one instance and selecting "rename variable".
We've added a new widget to the Komodo statusbar called Breadcrumbs. Clicking on the file entry, you can access any of its parent items, which gives access to the directory above each item. You can easily navigate this structure to open related files. As you change files, Breadcrumbs updates itself to your relative location. You can also use the keyboard to navigate Breadcrumbs.
You can now define multiple selections. As you edit one of your selected locations, every other location you have selected will reflect your edits. You can quickly add selections using CTRL (or Command)+D.