disable a button if no active workbook

[hoadiem]

Hi, all

I am doing a custom excel addin in vsto , i want to be able to disable buttons in the ribbon (in my excel addin) if no active workbook open.
just like when you close out all workbook , you will see all the build-in buttons from excel are greyed out except a few still enable.

is it possible to do it ?

some thing like this ? I'm using C#

addin on load event ()
{
if (Excel.Workbook wb == null) // this code is wrong
{
     button.Enabled = false;
}
else
{
     button.Enabled = true;
}
}

thank you