Hello,
I encountered something to that, even though I have worked it out for
myself, I thought should be passed on.
While I was debugging an event handler (Validating) for a masked edit
box, I suddenly found myself 'back in the UI'. The line of code that
precipitated the surprise exit from the event handler to the UI happened to
generate a null reference exception, but no detectable exception was reported
(either in the IDE debug run or in the released program).
The line of code was not in a try/catch block (there are others in the
handler and, when appropriate, they are triggered). It was the true source
of the bug being worked on, but it was not detected until much later in the
code because as far as anyone knew the event handler validated the control
quite nicely.
I figure that whatever 'hidden' code calls the event handler does so from
within its own try/catch block. When it encounterd this particular
exception, it simply returned execution to the 'UI thread' (no explicit
multi-threading was used in the program, that descriptive phrase was intended
to limit verbiage (looks like I failed there)).
I don't know if this is just an issue with the masked edit box or with
more controls.
Thought you'd like to know,
mklapp