Need to measure tab button's border-box width or margin-box width, not its content-box width.   The old code just happened to work before (more or less) because the button didn't have any padding on it's outer node.   Fixes #15895, refs #14663 on trunk/ !strict.
Need to measure tab button's border-box width or margin-box width, not its content-box width.   The old code just happened to work before (more or less) because the button didn't have any padding on it's outer node.   Fixes #15895, refs #14663 on trunk/ !strict.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@29566 560b804f-0ae3-0310-86f3-f6aa0a117693

redaktor/deliteful