Change color of a Gtk::Entry stored in a specific variable - c++

Question

I am looking for a way to change the color of a Gtk::Entry that is stored in a specific variable. I am using the CSS way to specify the color of an Entry and I have found this code which changes the color of all entries in the application but this is not exactly what I am looking for:
styleContext = get_style_context();
provider = Gtk::CssProvider::create();
styleContext->add_provider_for_screen(Gdk::Screen::get_default(), provider,
GTK_STYLE_PROVIDER_PRIORITY_USER);
provider->load_from_data(".entry { background: red; }");

Answer 1

You can get the style context for that particular Gtk::Entry, it can look someting like:
auto style_context = entryWidget.get_style_context();
try {
auto red_background = Gtk::CssProvider::create();
red_background->load_from_data(" entry { background: red; } ");
style_context->add_provider(red_background, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
} catch (Gtk::CssProviderError& err) {
std::cerr << err.what() << "\n";
}
Sometimes it is tricky to have the style apply to the widget. If this is the case, try changing the selector from tag entry to *.
The API docs suggests it is possible use an id selector in the css and apply the css-provider to the parent Window. I have not been able to make this work.