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Navigation:  Language Reference > 9 -  Window and Report Attributes > Window and Report Attributes >====== MDI (set MDI child window) ====== Previous pageReturn to chapter overviewNext page




The MDI attribute (PROP:MDI, read-only) specifies a WINDOW that acts as a “child” window to an APPLICATION. MDI windows are clipped to the APPLICATION frame–they display only in the APPLICATION's client area. MDI windows automatically move when the APPLICATION frame is moved, and are totally concealed by minimizing the APPLICATION. An MDI WINDOW cannot open until there is an active APPLICATION.

Modeless Windows


MDI “child” windows are modeless; the user may change to the top window of another execution thread, within the same application or any other application running in Windows, at any time. An MDI “child” window must not be on the same execution thread as the APPLICATION. Therefore, any MDI “child” window called directly from the APPLICATION must be in a separate procedure so the START procedure can be used to begin a new execution thread. Once started, multiple MDI “child” windows may be called in the new thread.

Application Modal Windows


A non-MDI WINDOW operates independently of any previously opened APPLICATION. It will, however, disable an APPLICATION if it or any of its MDI “child” windows are on the same execution thread as the non-MDI window. This makes a non-MDI window opened in an MDI thread an “application modal” window which effectively disables the application while the user has the window open (unless it is opened in its own separate execution thread). It does not, however, prevent the user from changing to another application running under Windows. An MDI window may not be opened on the same thread as an already open non-MDI window.


Win2 WINDOW,MDI      !An MDI child Window


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mdi_set_mdi_child_window_.htm.txt · Last modified: 2021/04/15 15:57 by