Not sure, but saving a pointer to the style before applying it does not suffice?

How will saving a pointer help me when I change the style? A pointer is just a pointer. I need a copy or clone functionality, or a way to do what QApplication does when starting up, that is, constructing the correct style for the current environment.

Perhaps you should try to rephrase what your real goal is. It is not very clear what you want to achieve in the end.

If what you want is to be able to switch back to your original style, maybe thru a menu item, something like this should suffice:

but as Andre stated, you should express better what is your aim, so we can help.

What I want is

• to be able to switch back to the old style
• to be able to explicitly set the old style on certain widgets

Actually, that is in interesting question. A quick documentation scan does not reveal an easy way to do this.

The main problem is, that the suggestion to just take the pointer and keep it around, and set it for the widgets you mention, will not work. QApplication will delete the curent QStyle object as soon as you set another one. That makes that you cannot really use the pointer anymore after that.

On the other hand, I do not see a way to query the name of the current QStyle. I might have overlooked it, but I would have expected QStyle to provide a name for the style. If you can find it, you can instantiate a new style object based on the name.

Andre wrote:

The main problem is, that the suggestion to just take the pointer and keep it around, and set it for the widgets you mention, will not work. QApplication will delete the curent QStyle object as soon as you set another one. That makes that you cannot really use the pointer anymore after that.

Confirm, in fact within QApplication::setStyle we have

being old the previous QStyle*. Being setStyle a static method there is no way with subclassing of change the behavior.

I guess the only solution is to create a data structure to store properties about the old style. Or to make a subclass that reveals the d-pointer, with of course a lot of portability issues…..

A style is a global object, you cannot set a different style for a selected set of widgets.

Of course style is shared among the whole application. The problem here was also about how to swtich back to an already used style.

fluca1978 wrote:

Of course style is shared among the whole application. The problem here was also about how to swtich back to an already used style.

That was one part. The other question was

Asperamanca wrote:

What I want is

• to be able to explicitly set the old style on certain widgets

You can set a style on a widget too. That is not the issue:

However, I guess you should heed the warning from the documentation:

Warning: This function is particularly useful for demonstration purposes, where you want to show Qt’s styling capabilities. Real applications should avoid it and use one consistent GUI style instead.

Well, I could do an ugly hack like this:

Andre wrote:

Setting a style on a widget will override the application style.

The widget style is usually the same for all widgets in an application (QApplication::style()), but it can be overridden on a per-widget basis using QWidget::setStyle().

Well, QStyle is an QObject, so retrieving the name of the current style is as simple as …

But the class name is not the same as the style name, that you need to instantiate it. Although, I think you might be able to instantiate the object using the class name.