Accessibility notes

• Status messages are announced to screen readers through a live region, including messages that are immediately followed by a screen change.
• When you move between screens, keyboard focus moves to the first meaningful element on the new screen (for example, the New Transmission button on the home page or the file drop zone on the Select Files step).
• Dialogs trap focus while open and return focus to the control that opened them when they close. Pressing Enter activates the primary button of the top-most dialog.
• The file drop zone can be operated from the keyboard: tab to it and press Enter or Space to open the file dialog.
• The IRS Environment toggle exposes its pressed state to assistive technology.