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qb64/internal/help/_SCREENEXISTS.txt

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2016-03-18 11:36:04 +00:00
{{DISPLAYTITLE:_SCREENEXISTS}}
The [[_SCREENEXISTS]] function returns a -1 value once a screen has been created.
{{PageSyntax}}
::: screenready = '''_SCREENEXISTS'''
{{PageDescription}}
* Function returns a true value once a program screen is available to use or change.
* Avoids program errors or omissions because a screen was not ready for input or alterations.
''Example:'' The loop waits until the screen exists to add the title.
{{CodeStart}} '' ''
{{Cl|SCREEN}} 12
{{Cl|DO}}: {{Cl|LOOP}} {{Cl|UNTIL}} _{{Cl|SCREENEXISTS}}
{{Cl|_TITLE}} "My Title"
{{CodeEnd}}
{{PageSeeAlso}}
* [[_FULLSCREEN]]
* [[_SCREENIMAGE]]
* [[$CONSOLE]]
* [[$RESIZE]]
{{PageNavigation}}