Problem with window repaint and scrollbars in edit mode (LabVIEW 8.0.1)

[pvanrompay]

I am running LabVIEW 8.0.1 in Windows XP SP3.  For my main VI, I ran into a strange problem about 5 months ago.  The front panel window - in both edit mode and run mode - stopped repainting itself on the right side which is most visible when you scroll up and down, but also visible with overlapping windows.  Coincident with the repaint problem, both scrollbars look disabled with greyed-out arrows and no boxes in the bars that you can click and drag to scroll the window.  The scrollbars still partially work if you hover the mouse over them and roll the mouse wheel but clicking and dragging doesn't work. 

The front panel has lots of controls and indicators including tab-control containers and is larger in the horizontal and vertical directions so both scrollbars should be active.  But I deleted all elements on the front panel and everything in the block diagram and the problem persists.  So the problem is not directly related to some control/indicator display.

I saved the simple VI with this problem (using a wide text line and a tall rounded box to test), then created a new VI and copied the two elements to the new VI.  This new VI does not have the repaint and scrollbar problem.  The two VIs differ slightly in memory usage and in revision number (the bad one is revision 1785 and the good one is revision 3), but otherwise the two VIs are identical.  I attached both VIs to this posting.  When you first open the bad VI, you'll see the disabled scrollbars whereas the good VI has active scrollbars.  To replicate the repaint problem, scroll the window up and down with your mouse wheel.  If it's fine when you first open the VI, click on another window, then click back on the VI window and try the mouse wheel again.  This clicking-away-and-back always causes the repaint problem for me.  I tried the VIs on two different computers both running Windows XP SP3 and LabVIEW 8.0.1 with identical results.

Here's what I discovered from troubleshooting with the simple VIs:

* scrollbars always disabled

* repaint problem in main window for window widths larger then 680 pixels

* repaint problem in main window menu toolbar for widths larger than 646 pixels

* entire window becomes disabled for window widths larger than 1348 pixels

* can repaint window by minimizing and restoring, but only repaints that one time

* scrollbar boxes sometimes flicker into view but then disappear

* scroll left and right by hovering mouse over horizontal scrollbar and using mouse wheel

I found something similar on this forum (thread: Problem with front panel refresh) - it might be related to the CAR about the panel being offset internally.  I don't have access to LabVIEW 8.5 or later and don't plan to upgrade - I haven't tried the trial version as that user did.  I could try to copy and paste my entire block diagram to a new VI but the VI is so large I'm afraid something would break, plus I don't want this to happen again in a few months.  The problem seemed to occur after a certain number of saves (or revision number).  I save backup copies often and when the problem first happened, I was able to go back to a previous version, make the missing changes and save it with no problems, but this only delayed the problem and it came up later.  So maybe it's the revision number.  It didn't seem related to a particular addition or modification in the front panel or diagram.

The image attached shows the repaint and scrollbar problems in the bad VI.

This brings up a question I have - if this problem is a bug and was fixed in 8.5 and later, is there a way to apply bug fixes to earlier versions?  Or do I have to pay for an upgrade to fix such bugs?

[altenbach · Accepted solution]

Seems something got corrupted with this VI. Copy things over to a fresh VI and things should be OK.

See also this recent report of a similar issue.