BUG: MOUSE(0) with WINDOW OUTPUT Gives Incorrect Coordinates (79118)

SYMPTOMS

In a compiled program, the MOUSE function incorrectly returns the position of the mouse pointer relative to the output window rather than the active window. This problem only occurs in compiled programs that use the WINDOW OUTPUT statement to direct output to a window other than the active window.

Microsoft has confirmed this to be a bug in Microsoft QuickBasic versions 1.0, 1.0a, and 1.0b for Macintosh . We are researching this problem and will post new information here as it becomes available.

MORE INFORMATION

Workaround

To work around this problem, set the output window to the active window using the WINDOW OUTPUT statement before calling MOUSE(0).

The function MOUSE(0) is designed to return the status of the mouse button and record the position of the mouse pointer within the active window. The x and y coordinates recorded by MOUSE(0) are returned by MOUSE(1) and MOUSE(2), respectively.

The active window is the highlighted, front-most window. It is the same as the output window unless the WINDOW OUTPUT statement is used to direct output to another window.

Steps to Reproduce Problem

The program example below demonstrates the problem. The program creates two windows titled "One" and "Two". When you press the mouse button while the mouse pointer is in window "One," the mouse pointer x and y coordinates are printed in window "Two."

When run in the interpreter environment, the x and y coordinates are correctly relative to the upper-left corner of window "One." When compiled, the coordinates are incorrectly relative to the upper-left corner of window "Two" (the values printed are negative).

WINDOW 1, "One", (10, 40)-(250, 160), 1
WINDOW 2, "Two", (250, 190)-(500, 320), 1

WINDOW 1                  ' the active window
WINDOW OUTPUT 2           ' the output window

WHILE INKEY$ = ""
   IF MOUSE(0) <> 0 THEN  ' mouse button down
      PRINT "x="; MOUSE(1); "y="; MOUSE(2)
   END IF
WEND
END

To work around the problem so that this compiled program behaves correctly, insert the statement "WINDOW OUTPUT 1" before the statement "IF MOUSE(0) ..." and insert "WINDOW OUTPUT 2" before the statement "PRINT "x=" ..."