GUI ScreenIO for Windows

Multiple Working-sets

A conventional GUI ScreenIO application only allows the user to work with the last window that your application displayed, even though previously displayed, underlying windows, are visible. Even if you click on these previously displayed windows, nothing happens until you close the last window displayed by the application. 

This is just fine for most applications, and is in fact how most Microsoft Windows applications work - regardless of the language used to develop the application.

Some applications, however, (including the GUI ScreenIO panel editor) allow you to switch between sets of windows.  In the panel editor, this lets you switch between two or more panels any time you want to; for example, you can take advantage of this to easily copy and paste controls from one panel to another.  You could also, for example, write an application which would allow the user to easily switch at any time between a name or part number search, and an order entry module.

This behavior is determined, in part, by whether your panels are "modal or modeless." 

Modal Panels

Most Windows applications - and most GUI ScreenIO applications - are composed of modal windows.  A modal window disables all of the other windows in the application when it is displayed, which prevents the user from activating another window until he/she has finished with the modal window. 

A good example of a modal window is the message box displayed when you select Help/About from the menu of most applications.  You can't switch to any other window in the application until you close the Help/About window by clicking the OK button.

You can usually switch to a different Windows application when an application displays a modal window.  Some windows (called "system modal") don't even allow this; system modal dialogs must be closed before you can do anything else in Windows.

Modeless Panels

Modeless windows allow the user to switch between windows in an application without closing them first, as with modal windows. 

A good example of a modeless window is the Find/Replace dialog in most word processors.  If the Find/Replace dialog box were modal, you'd need to launch it from the menu every time you wanted to use it, which would be very inconvenient.  Because the Find/Replace dialog is a modeless window, however, you can freely switch between it and your document.

Modeless panels come with a penalty, however; if you use them, you need to work a little harder.  The reason is, your program must be written so that it can accommodate the user switching from one window to another. 

If you think about it, you'll notice that most applications limit how much window-switching you can do; it's fairly uncommon to encounter applications that let you switch between more than two windows at a time.  Now you know why; the more modeless windows that you display concurrently, the more complex your window-management logic must be. 

Modeless Panels and GUI ScreenIO

GUI ScreenIO implements modeless panels through the use of working-sets.  A working-set consists of a related set of panels that are modal within the set, but modeless with respect to other sets.   

Just as in a conventional modal GUI ScreenIO application, only the last panel displayed in a given working-set is active - but you can switch between working-sets.

Sample Application

We have a sample application available on our Download Page that demonstrates ALL of these modes.

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