As the method impl suggests, the left value is preferred if all the values are the same.
This is the case for the given layout.
```cpp
int QLayout::margin() const
{
int left, top, right, bottom;
getContentsMargins(&left, &top, &right, &bottom);
if (left == top && top == right && right == bottom) {
return left;
} else {
return -1;
}
}
```
QHBoxLayout* layout = new QHBoxLayout(this);
layout->addWidget(m_preview);
- layout->addSpacing(layout->margin());
+ layout->addSpacing(layout->contentsMargins().left());
layout->addLayout(textLayout);
}