RosettaCodeData/Task/Window-creation/XPL0/window-creation.xpl0

\012345678901234567890123456789012345
\ Window creation...............  X .

def  X0=20, Y0=10;              \position of upper-left corner of window (chars)
int  Mouse, Button, X, Y;

func GetButton;                 \Return soft button number at mouse pointer
[Mouse:= GetMouse;              \get pointer to mouse array information
X:= Mouse(0)/8  - X0;           \convert pixels to 8x16-pixel character cells
Y:= Mouse(1)/16 - Y0;
if X>=32 & X<=34 & Y=0 then return 0;   \exit [X]
return -1;                      \mouse not on any soft button
];

[SetVid($12);                   \set 640x480 graphics
TrapC(true);                    \prevent Ctrl+C from aborting the program
Attrib($70);                    \set black-on-gray color attribute
SetWind(0+X0, 0+Y0, 35+X0, 8+Y0, 0, \fill\true);        \draw gray rectangle
Cursor(33+X0, 0+Y0);  Text(6, "X");                     \draw exit button
Attrib($9F);                    \set bright white on light blue, for title bar
Cursor(0+X0, 0+Y0);  Text(6, " Window creation               ");
ShowMouse(true);                        \turn on mouse pointer
loop    [MoveMouse;                     \make pointer track mouse movements
        Mouse:= GetMouse;               \get pointer to mouse array information
        if Mouse(2) then                \a left or right mouse button is down
            [Button:= GetButton;        \get soft button at mouse pointer
            while Mouse(2) do           \wait for mouse button(s) to be released
                [MoveMouse;
                Mouse:= GetMouse;
                ];
            if Button = GetButton then  \if down Button = release button and it
                if Button = 0 then quit; \is the exit [X] button then quit loop
            ];
        if KeyHit then                  \get character from non-echoed keyboard
            if ChIn(1) = \Esc\$1B then quit; \Esc key also exits program
        ];
SetVid(3);                              \restore normal text mode immediately
]