Just noticed this tonight:
1. Copy a line of source code into your clipboard (Ctrl-C). Keep the highlighting all on one line--don't highlight vertically.
2. Open a new source file. Cursor will be positioned at line #1, column #1.
3. Paste the line of source from the clipboard (Ctrl-V)
4. Move to the end of the source file with the keyboard shortcut (Ctrl-End)
If it is going to happen to you, then you will notice that your cursor is positioned at line #2, column #1 yet there is no line number for line #2.
5. Repeat until you get bored.
Your choice:
6a. Press ENTER. The line numbering will resume properly, but only on the new line and below.
-or start over, repeat up to step 5, and try...-
6b. Change focus to another application, and then return to CVI (Alt-Tab x2). Now all line numbers are corrected when the IDE is redrawn.
-or-
6c. Highlight one or more un-numbered lines of source code (vertically) and delete them (Del). Now all lines are re-numbered by the deletion.
Orlan
