I notice that there is no easily-identifiable way of creating a tooltip in the BeOS (Firefox seems to use a BWindow class, with the result that tooltips create a spurious blank entry on the Deskbar) so I suggest the inclusion of a BTooltip or BPopupHint class into Haiku’s app_server.
There is no good way for a window to indicate on the Deskbar that it requires attention like Windows’ flashing taskbar entry, OSX’s bouncing icon or Linux’s URGENT hint sent to the window manager (IM Kit includes a square-root symbol masquerading as a tick into the title of the IM window, but this is a per-application setting) so I recommend that three new forms of BMessage be accepted by the Deskbar - B_INFO_INDICATOR, B_ALERT_INDICATOR and B_WARNING_INDICATOR - which would display icons on the Deskbar indicating the level of urgency.
Firefox uses it’s own API for creating tooltips on all platforms which are nsWindows. In BeOS that’s implemented by BWindow (and others).
Having a tooltip class wouldn’t be bad though.