No way of displaying a tooltip in fallback mode

[Guido Berhoerster]

Current status notifier/application indicator implementations such as KDE Plasma or the Xfce Status Notifier Plugin display the indicators "title" and "icon-desc" or "attention-icon-desc" properties in a tooltip. In fallback mode, i.e. when the icon is a tray icon, does not show a tooltip and neither provides an API to make use of the tooltip functionality of the GtkStatusIcon.

This is specifically a problem for my project package-update-indicator which notifies of available package updates with an icon. If users miss the associated notification or do not use a notification daemon it is rather confusing without a tooltip providing the name of the indicator it belongs to as well as an brief explanation like "Updates available".

I've created a patch which replicates the behavior of KDE Plasma or the Xfce Status Notifier Plugin in fallback mode by displaying a tooltip with the contents of the "title" and "icon-desc" or "attention-icon-desc".