🚀 go-pugleaf

I have a previewer application that checks every few seconds whether
the file it is displaying has changed.  If it finds it has changed
it goes ahead and repaints the screen.  Some other application creates
(compiles) the file.  

The user typically will use an editor in one Windows to edit the source
file, then run an application in another Window that `compiles' it, while
viewing the result in a third Window. I want the viewing part to be
automatically updated when the file is changed, (without explicit 
communication between the `compiler' and the `viewer').

Things work OK, if I do NOT have SHARE.EXE installed.  If I do, I start to
get sharing violations.  I've tried several combinations of flags for
OpenFile without any luck.  I thought SHARE was supposed to help
applications that want to get at the same file!  

So my question is, how can I determnine whether some other application has a
particular file open so I don't try to open it and get slapped across the
wrist?  What combination of flags in OpenFile gives me some code that
tells me the file is in use (or hangs me up until it it not), WITHOUT
giving me these unpleasant `sharing violations'?

Thanks.

Berthold K.P. Horn
Cambridge, Massachusetts, USA