Whenever the user interacts with an <input type='color' /> HTML element, WebKit will need to show a dialog to choose a color. For that to happen in a general way, instead of just opening a #GtkColorChooser (which might be not desirable in some cases, which could prefer to use their own color chooser dialog), WebKit will fire the #WebKitWebView::run-color-chooser signal with a #WebKitColorChooserRequest object, which will allow the client application to specify the color to be selected, to inspect the details of the request (e.g. to get initial color) and to cancel the request, in case nothing was selected.