Progress
Language Tutorial
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Using Basic Control Mechanisms
Basic control is the ability to put up a functioning interface and allow your users to interact with it. The WAIT–FOR statement is the statement that blocks the execution of an application and specifies an end condition that signals Progress to end the current module and continue processing or exit.
Only one WAIT-FOR statement should be active at once. Multiple WAIT-FOR statements can interfere with each other, unless you take explicit control over enabling and disabling all widgets to prevent conflicts.
It is also true that the implied execution blocking that comes with the UPDATE statement and related statements should not be mixed with a WAIT-FOR in the same interface, for the same reasons. UPDATE statements with dialog boxes work well together because the disabling of the main interface by the dialog box allows the UPDATE to function without interference from the main WAIT-FOR.
In most cases, an application should have only a single active WAIT-FOR. Secondary interfaces should use another technique to block execution.
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