prevent selection in QComboBox.

[jpn]

the component here is constraint by the available dialog box space => QComboBox is suitable ?

Ok, let's say it is. But combo box is also a well known and widely accepted UI component. People expect it to behave in a certain way. What's the problem with disabling it? That's the normal way of preventing selection... But making it semi-disabled in the sense that you can pop up the view but you still can't change the selection will most likely just confuse end-users, because that's not what people are used to.

You could set a custom model for your combo box. Then you can return the appropriate flags.

Sure it's possible. There's a solution somewhere on this forum. But the question is... is it really a sensible thing to do?