Run addin macro on selection change

Hi

I have made a custom addin for myself to do things such as show/remove the tabs on the current workbook, manupulate data etc. I also made a custom toolbar to acces these macros.

Does anyone know of a way I can have a macro in this addin automatically run on the current selection changing in whatever workbook is currently open (or on that workbook being closed, a new one being opened etc) so that I can make the buttons in the toolbar become greyed out if there is no current selection, no workbook open etc.

Thanks

Look at APplication.Run in VBA help.