Bug 181158 – Horizontal margins are not collapsed for children of <mrow>

• Component: MathML
• Status: RESOLVED INVALID

[Minsheng Liu]

Created attachment 330190 [details]
Horizontal margins are not collapsed for children of <mrow>

See the attachment for an example.

The reason comes to the following code:

RenderMathMLRow::layoutRowItems

for (auto* child = firstChildBox(); child; child = child->nextSiblingBox()) {
    // ...
    horizontalOffset += child->marginStart();
    // ...
    horizontalOffset += childWidth + child->marginEnd();
}

RenderMathMLRow::getContentBoundingBox

for (auto* child = firstChildBox(); child; child = child->nextSiblingBox()) {
    // ...
    width += child->marginStart() + child->logicalWidth() + child->marginEnd();
    // ...
}

I think we should really ignores margin/padding/border for MathML elements. It appears that Firefox does that.

[Minsheng Liu]

I did not realize that margin collapsing only happens for margin-top and margin-bottom.