Multiple Windows in PhpStorm

PhpStorm supports only one frame per project.

Note that you can drag editor tab outside of the main window to create another window for the editor. Tool window panels can be also detached and moved to to the second display if you so desire.

You can choose Split Horizontally or Split Vertically from Windows menu!

As they are so useful, you can put two shortcuts to use them easier. I put option + 1 for splitting vertically and option + shift + 1 for splitting horizontally.

Update In 2017 versions, The Split Horizontally and Split Vertically options are located into Windows > Editor Tabs

I was going to add this as a comment, on Nima Ghaedsharafi's post. The path to '''Split Horizontally''' and '''Split Vertically''' looks to be '''Window > Editor Tabs > Split ...''' in Version. 2017.1.4