At last, I found the error

General
1

I had sometimes ago an error in project and I could not found why.

That’s done. I now know what happened.

I stored a string in RowTag,
later / elsewhere, I read that RowTag and fill a FolmderItem variable with it. LOOK:

LB.RowTag(0) = Master_Data_FI.Name
Character_FI = LB.RowTag(0)

Of course, this cannot (must ?) not work. I will correct that in my project.

I restate the example with more speaking code:
FolderItem = String

Yes, I know, RowRag is a Variant, so I do not know what it is doing, but I suppose this is a bug (yes, mine at first, but Xojo too)
In the debugger, the line goes on, then I fall into the BackgroundPaint Event, and when I get back… crash.

2

I would have expected the above to give a runtime exception.

Specifically, an illegalCastException, with the message

_VariantString cannot be cast to FolderItem