How can a WPF StackPanel fill vertically from bottom to top?

Question

I need to be able to fill a stackpanel with buttons but the buttons must appear at the bottom of the stackpanel first and populate upwards<

Answer 1

Love the transforms solution by Nir. I was wondering if it could be done using transforms.

One caveat, though: Don't use the transforms trick on a ScrollView based control such as a ListBox because the scroll bar operation will be inverted from the content. Hilarious to watch, as long as you're not the end user. ;>