Selectable with a calendar type layout

Selectable with a calendar type layout

Can't seem to wrap my head around this...

Is it possible to use selectable on a calendar type layout (table based with rows = weeks, cells = days) such that when selecting across rows it will select all the appropriate cells? I can get it to work when selecting "down" (i.e. start at the 2nd and select down to the 18th) - but that's about it. I can't seem to figure out how to get the unselecting to work or the "upward" select (i.e. start at the 28th and select up to the 10th).

any help is appreciated.

- neil