In QBX 7.10, F8 Step then Editing Active Statement Can Fail (67363)

SYMPTOMS

When you single step (F8) through a program in the QBX.EXE version 7.10 environment, editing the active (highlighted) statement can give unexpected results under certain circumstances. For example, if you attempt to split the active line in two by pressing the ENTER key, the next line may duplicate the current line. Sometimes the first line splits correctly but the next line becomes an altered version of the first line. Note that pressing "ALT+BACKSPACE" will usually undo the editing problem.

STATUS

Microsoft has confirmed this to be a bug in the QuickBasic extended environment (QBX.EXE) that comes with Microsoft Basic Professional Development System (PDS) version 7.10 for MS-DOS. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This problem can occur on any statement where a variable is first declared, including the following statements: COMMON SHARED, DIM SHARED, REDIM, FOR, WHILE, DO...LOOP, or IF. When creating the problem with FOR, WHILE, DO...LOOP, or IF statements, you must actually try and divide the Basic reserved word (for example, put the cursor in the middle of WHILE and press ENTER).

To reproduce the problem, perform the following steps:

Add the line below to the beginning of an empty program window:
COMMON SHARED A, B
Make the line the current executing line by single stepping with the F8 key until that line is highlighted.
Now put the cursor anywhere before the "B" (for example, put the cursor on the "A") and press ENTER.
A dialog box will appear saying "You will have to restart your program after this edit. Proceed anyway?" Press ENTER.

Your source code will now resemble the following:

      COMMON SHARED A
      COMMON SHARED A, B

To reproduce the problem with an assignment statement, enter the single Basic line of code "x = a + b + c" and follow the steps above. When the line is highlighted, place the cursor on the variable "a" and press ENTER. This will not duplicate the current line but will cause the "+" to be deleted between a and b.