Font and Color selection dialogs/widgets
GTK3 offers two versions of widgets and dialogs for font and color selection. Two older objects are called GtkFontSelection and GtkColorSelection. Two newer are called GtkFontChooser and GtkColorChooser. The older widgets are deprecated but still can be used by applications.
Honestly, I do not like newer versions very much. While the FontChooser at least looks elegant, I can not say the same about the ColorChooser; its usability is doubtful too. I guess that newer widgets were prepared for using with touch screens, which is not very popular use case, at least currently.
Anyway, REdit gives the choice. The user can select what dialog would be launched: the one based on a classic widget or the dialog based on the new one.
Classic Font Selection Dialog
New Font Selection Dialog
Classic Color Selection Dialog
New Color Selection Dialog