No cancel or close button on the "Create a new script" dialog on Linux

[Natan Organick]

When the "Create a new script" button is clicked on Linux, the dialog box does not have a cancel button or a close button. In order to exit the dialog you must either press the Escape key or create a new script from one of the language options.

The dialog on Mac does have a red close button on the dialog (in addition to the Escape key working).