User Control Odd Behaviour

[Jeff Gaines]

I have written a 'File Manager' control which combines a TreeView and
ListView and incorporates Explorer's Context Menu.

The Solution contains three projects, the control plus two test apps.

I am seeing different behaviour from the control depending on which
test app I run, VS.NET seems pretty good at keeping the versions up to
date but I have manually deleted and re-added the control but it makes
no difference to the behaviour.

When I right click on a file in TestApp1 the context menu appears and
the 'Open With' item gives the choice of 4 program plus 'Choose
Program...'.

In TestApp2 choosing the same file the Context Menu only gives a
choice of 2 programs (plus 'Choose Program...').

This happens with several different file types.

All the code is in the control itself, not in the test apps.

I really don't know where to start looking for an explanation of this,
I thought that having designed a control it would behave the same
wherever it was used.

I have even used two different methods of calling the Context Menu,
one is 'native' (in C#), the other is a DLL built in C, whichever I
use I still get the same behaviour.

Can anybody give me any guidance on ensuring the control behaves in
the same way wherever it is used? It makes debugging and testing
interesting with this inconsistency :-))

Many thanks.

--
Jeff Gaines Damerham Hampshire UK