The Layer dialog calls SPItem::setHidden() which sets the 'display' property directly without setting the style_src variable which is initialized to SP_STYLE_SRC_UNSET. As writing properties directly is likely to exist throughout Inkscape's code base, it is probably safer to initialize style_src to SP_STYLE_SRC_PROP.
The Layer dialog calls SPItem::setHidden() which sets the 'display' property directly without setting the style_src variable which is initialized to SP_STYLE_SRC_UNSET. As writing properties directly is likely to exist throughout Inkscape's code base, it is probably safer to initialize style_src to SP_STYLE_SRC_PROP.