_ALLOWFULLSCREEN - QB64Official/qb64 GitHub Wiki
The _ALLOWFULLSCREEN statement allows setting the behavior of the ALT+ENTER combo.
Syntax
_ALLOWFULLSCREEN [{_STRETCH|_SQUAREPIXELS|OFF|_ALL}][, {_SMOOTH|OFF|_ALL}]
Description
- Calling the statement with no parameters enables all four possible full screen modes (and is the default state when a program is started): both _STRETCH (_SMOOTH and _OFF) and _SQUAREPIXELS (_SMOOTH and _OFF).
- Using _ALLOWFULLSCREEN _ALL, _ALL has the same effect.
 
 - _ALLOWFULLSCREEN only affects the behavior of ALT+ENTER. The _FULLSCREEN statement is not bound by _ALLOWFULLSCREEN's settings so all modes can be accessed programmatically.
 - To limit just the mode but allow both _SMOOTH + _OFF antialiasing modes, pass just the first parameter: Example: _ALLOWFULLSCREEN _SQUAREPIXELS
 - To allow multiple modes with _SMOOTH or _OFF as default, pass just the second parameter. Example: _ALLOWFULLSCREEN , _SMOOTH
 - Any possible permutation of the parameters is allowed.
 - With _ALLOWFULLSCREEN _OFF you can trap Alt+Enter manually in your program and reassign it. See example 2 below.
 
Availability
- Version 1.3 and up.
 
Example(s)
Allowing only one full-screen mode with square pixels and no anti-aliasing:
_ALLOWFULLSCREEN _SQUAREPIXELS, OFF
Disabling _FULLSCREEN with Alt+ENTER so the combo can be manually trapped:
DO
    CLS
    LOCATE 7
    PRINT "    - Press ALT+ENTER to test trapping the combo..."
    PRINT "    _ Press SPACEBAR to allow fullscreen again..."
    k& = _KEYHIT
    IF k& = 13 THEN
        IF _KEYDOWN(100307) OR _KEYDOWN(100308) THEN
            altEnter = altEnter + 1
        END IF
    ELSEIF k& = 32 THEN
        fullscreenEnabled = NOT fullscreenEnabled
    END IF
    LOCATE 14
    IF fullscreenEnabled THEN
        _ALLOWFULLSCREEN _ALL, _ALL
        altEnter = 0
        PRINT "_ALLOWFULLSCREEN _ALL, _ALL"
        LOCATE 18
        PRINT "ALT+ENTER will trigger all four fullscreen modes now."
    ELSE
        _ALLOWFULLSCREEN OFF
        PRINT "_ALLOWFULLSCREEN OFF"
    END IF
    IF altEnter THEN
        LOCATE 18
        PRINT "ALT+ENTER manually trapped"; altEnter; "times."
    END IF
    _DISPLAY
    _LIMIT 30
LOOP