I just tried the Tabs tutorial and tried running it with auto_size both on and off for the tabs and it doesn't seem to make any difference. The tabs are always stretched to fill the entire window width. Shouldn't they scale down to fit just the size of the text for each tab when auto_size is turned on?

auto_size makes each tab width dependent on the text (so one tab can be bigger than the other)

Oh ok, so that means if you had just one tab, it would still stretch across the entire width rather than just being big enough for the text in it?

yes