I have an application and I want to show a tooltip every time a user set the focus on a entry widget. Do you know a way to force a gtk Tooltip to be shown?, because right now it only shows when the user puts the mouse pointer over the entry, but the application in production will have no mouse at all.
You can't force the tooltip to show, but you could try making your own tooltip-like window using stuff like gtk_window_new(GTK_WINDOW_POPUP) and gtk_window_set_type_hint(window, GDK_WINDOW_TYPE_HINT_TOOLTIP). Then you can show this window at any time and place you choose. You might want to look at the source code of GtkTooltip to see how they implement the tooltip windows.