The mystery of the missing bug

I was working on the next version of OverviewCheck. I had tested about a dozen overviews, then I backed up to the first to watch them again, when - to my great surprise - every other overview came up blank. I did a little basic debugging, but found nothing that immediately stood out. Since the deconstructing of the overviews involve some rather complicated routines, I decided to go back to the previous version to see if the bug was there as well. It would be easier if I know for sure that it was caused by something I just had added.

Well, the previous version worked quite well, so I went back to my development version to dig deeper into the code. But now everything worked OK in this one as well! Try as I might I could not reproduce the problem again. This bugged (!) me no end. Seeing a problem and then not being able to reproduce it is so frustrating. Especially such a weird problem. I cannot fathom what could cause a flip-flopping like that.

There is of course the minute possibility that the problem isn't in my code at all, but some anomaly in Visual Studio when the program is run within Visual Studio. But that's extremely unlikely.

Since I can't reproduce it, I am still not 100% sure that it doesn't exist in the currently released version. If anyone experiences this problem in the current version (or in the next one, when it is released), I would surely like to hear about it. And if possible what lead up to the problem. This is a puzzler that I really would like to figure out!

As always - thanks for your input, mediadogg!

No background threads except when loading the XML, so that's not it.

All error handling is routed to the same place, popping my custom error window, so unlikely problem. I use a MZTools macro to insert try/catch code, where the catch code is just a call to a shared (static) subroutine in my error handling class. So all error catching should work the same.

The weird thing was that it was not at all random. Exactly every other review came up blank. I'm officially stumped. 

Another update, again?

Ah, yes. Somehow my brain seems to start working overtime after I release a version.   



I realized that unrecognized words that occur more than once probably are not misspelled. So I have chosen to underline them in orange. All to put the main focus on the most likely suspect words. But remember that even repeated words can be misspelled. I have seen it happen.

So this is now version 3.4.0. And the help file has been updated.

The flip-flop bug revealed


I just found the reason for the flip-flopping overview "bug". Basically it has to do with how events are handled in WPF. If you catch an event like KeyDown and do something - like reading in the next profile - WPF will still continue processing the event unless you tell it differently. So Right Arrow will do whatever Right Arrow does. If the keyboard focus is on the RichTextBox that displays the overview, the new overview will load, moving the keyboard cursor to the start, and then the cursor will move one character to the right.

And that's fine. You probably won't even notice it. However, if the focus should for some reason be on the Overview tab itself, something entirely different happens. The focus moves to the next tab. And that switches the tabs so the Notes tab is shown. And unless you've made any notes, it will be a blank tab.

So I saw the new cover image come up in the right half of the window, and saw the left half of the window go blank. I didn't notice that it was no longer the Overview tab, but rather the Notes tab. And of course pressing the Right Arrow again would switch it back to the Overview tab. DOH!

So, it's not so much a bug as it is unwanted behavior. If I had just been a tiny bit more observant when it happened, I could so easily have prevented it. Double DOH!

Thanks mediadogg, but since this is WPF, the simple solution is
e.handled = True
after doing the work in the handler.

Setting isTabStop to False for the TabItems would also have avoided the problem.
But 20/20 hindsight is always easy. 

Quoting mediadogg:

Quote:
I don't see why e.handled = true would solve the issues that I mentioned.

Ah, no, what I meant was that it was the way to solve my problem.

Quote:
I don't know WPF. Maybe I should.

Well, there is definitely a learning curve going from WinForms to WPF. But I definitely feel that it's worth it. I made the switch many years ago, and I have never gone back to WinForms.

That's one more great little project under your belt, Gunnar! Congratulations! 

But you do need to tell us more about Danish beer commercials! 

Nope. never saw that one - probably it's not being used over here. But I get it now. Nicely done, by the way.
Although... Carlsberg: best beer in the world? You and I know better.