Fix tabbed/stacking container height regression

Commit c2d6aff added a bounds check on `height - title_bar_height`,
repurposing the local variable `height` in an attempt to DRY out the
expression.

However, because re-assignment occurs inside the loop body, its result
would leak across loop iterations, compounding its effect and leading
to the artifact reported in issue #8625, where each child except the
first in a tabbed container would acquire a visible waterline.

Introduce a second variable and reset it in each loop iteration to get
rid of the waterline.

Fixes #8625.

0 files changed, 0 insertions, 0 deletions