file-menu:open

This method is called when the open menu-item of the file-menu menu is selected. If file-menu:open is bound to #f instead of a procedure, the open menu item will not be created.

• (send a-drscheme:frame:basics-mixin file-menu:open item evt) -> void
      item : (instance (derived-from menu-item%))
      evt : (instance control-event%)

  Calls handler:open-file to open a new file. Note that there is a handler installed already that opens all files in DrScheme frames.