In
user interface design, a
modal window is a
graphical control element subordinate to an application's
main window which creates a
mode where the main window can't be used. The modal window is a child window that requires users to interact with it before it can return to operating the
parent application, thus preventing the
workflow on the application main window. Modal windows are often called heavy windows or
modal dialogs because the window is often used to display a
dialog box.