Created attachment 201851 [details] [review]
notebook: properly subtract the initial_gap width from the tab space

Instead of modifying the allocation.

Created attachment 201852 [details] [review]
notebook: use the current page allocation when computing the redraw area

Instead of taking the first page and trying to adjust the rect with
random padding values, take the current page, as it's always guaranteed
to be at least as tall as inactive tabs.
This fixes some annoying 1px drawing artifacts while switching tabs when
the theme disables notebook padding.

Attachment 201851 [details] pushed as f01162c - notebook: properly subtract the initial_gap width from the tab space
Attachment 201852 [details] pushed as 79bbce5 - notebook: use the current page allocation when computing the redraw area

Pushed to master