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Task/GUI-component-interaction/00DESCRIPTION

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+Almost every application needs to communicate with the user in some way.
+Therefore, a substantial part of the code deals with the interaction of program
+logic with GUI components. Typically, the following is needed:
+
+* put values into input fields under program control
+* read and check input from the user
+* pop up dialogs to query the user for further information
+
+The task: For a minimal "application", write a program that presents a form with
+three components to the user: A numeric input field ("Value") and two buttons
+("increment" and "random").
+
+The field is initialized to zero. The user may manually enter a new value into
+the field, or increment its value with the "increment" button. Entering a
+non-numeric value should be either impossible, or issue an error message.
+
+Pressing the "random" button presents a confirmation dialog, and resets the
+field's value to a random value if the answer is "Yes".
+
+(This task may be regarded as an extension of the task [[Simple windowed application]]).