First of all, thumbs up for your Web IDE / PhpStorm project.
I am a Wacom (pentablet) user. The Wacom pens have two buttons, from which one of them is configured as 'double click'. Using that button, I cannot open files in the project tree on the left. In the editor, the doubleclick button works fine, but in the project tree it doesn't. It simple does not recognize the doubleclick, except when I hold the pen completely still.
The strange thing is, I do not have to hold it still for opening folders; they open or collapse just fine using the doubleclick button. So it looks the behaviour of opening/closing folders is different from opening files, when it comes to doubleclick event handling.