why add the int if you're not going to use it?

use a lambda here:

• avoids the single-use emitCommitData wrapper
• avoids the need for qobject_cast<QWidget*>(sender()), which is the combobox (just capture it).

I think instead of emiting KFilePropertiesPlugin::changed() it would be better to call setDirty() in the slots.

See https://api.kde.org/frameworks/kio/html/classKPropertiesDialogPlugin.html#af25f4b84d915dcc005a203a637ad0511

I'd love to, and I tried, but this stuff is pretty new to me and I kept getting error: cannot define member function What's wrong with this?

connect(comboBox, &QComboBox::activated,
        [comboBox]() { emit commitData(comboBox); });

QComboBox::activated passes an int argument along that as far as I can tell (I could be wrong) needs to be handled by the function it's connected to

commitData is an inherited member function from QItemDelegate, i.e. you have to also capture this

without having tried it, you probably still need the QOverload to say which activated version you want, so

connect(comboBox, QOverload<int>::of(&QComboBox::activated), this, [this, comboBox] { emit commitData(comboBox); });

nah, the right hand side needs to be a subset of the left hand side (or be able to convert from one to another)

Nope, same issue I'm afraid.

GCC 8.3.1 gives me a helpful error message:

...samba/filepropertiesplugin/delegate.cpp: In lambda function:
...samba/filepropertiesplugin/delegate.cpp:48:58: error: passing ‘const UserPermissionDelegate’ as ‘this’ argument discards qualifiers [-fpermissive]
         [this, comboBox] (int) { emit commitData(comboBox); }

this is const as createEditor(...) is const. Apparently connect discards the constness of this.

But reading through https://doc.qt.io/qt-5/qtwidgets-itemviews-spinboxdelegate-example.html , it seems like the connect is not needed at all. The selected value is propagated via setModelData.

Can you test if it still works when you remove the whole connect(...) here?

I meant - do setDirty() in e.g. checkShareName(), i.e. only one connection per signal.