771051 - nsTextFrame paints all decoration lines two or more times if selected

Status: NEW

(Core :: Layout: Text and Fonts, defect)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

nsTextFrame paints all of decoration lines every drawing segment separated by selection.

See the URL:
data:text/html,<span style="font-size: 60px; text-decoration: underline overline line-through; color: rgba(0%, 0%, 100%, .2);">foo <span>bar</span></span>

The color of the foreground color has transparency (0.2). When you select a part of "foo " or "bar", only the decoration lines become more opaque color.

I think that nsTextFrame separates the painting code of decoration lines from drawing text.

I see another issue by same bug:

data:text/html,<span style="text-decoration: underline overline line-through; color: blue; font-size: 40px;">foo <span style="font-size: 8em; color: red; vertical-align: middle;">bar</span></span>

When you select "b", you can see underline and overline over the selected "b".

When you select "r", you can see underline and overline over the non-selected "ba".

This might be a regression of bug 403524, but I'm not sure.