Hi,

I am creating buttons on a spreadsheet through a C# code from an add-on
module.

The functionality is implemented and works. My problem is that this module
is run at a relatively radom time, so it sometimes bumps into situation when
the active sheet is not available for writing - for example when there is a
modal Excel dialog window open.

My question is: How can I detect such conditions in order to avoid running
my code in such moments? Probably I just need a hint to start from.

Another important information is that my add-on uses separate thread to
access the Excel object.

Thank you for your time,
Nacho