You could probably also use a spacer item to "add" the title width constraints to the usual layouting mechanism.

Depending on the size policy this could allow uses to make the window smaller if they wanted to, while still having the fully expanded dialog by default.

Btw, it is usually not custom to pass a QString by pointer, i.e. by value or const reference are what you will find in most cases.
Avoids either having to rely on the caller or having checks inside the callee.

Cheers,
_