I'm using the TreeView and a ListStore to display tables of data.

Users often want to sort on a particular column or filter to see a subset of the
values in a particular column.

The TreeView has excellent support for the former -- I just need to make the
column headers clickable and I pretty much get the sorting for free.

For the latter I'd like to have it so that right-click on a column label will
pop up a simple dialog which allows the user to select which values they want to
see.   (as an aside, kudos for the latest gtk which has support for a filtered
model, very handy for the filtering part).

Unfortunately, there is currently no way to get at any other events that occur
on the column headers.

It would be nice if a right click (or Enter key when the column header has
focus) generated a popup-menu signal, so that application code could provide a menu.