Tooltips are a visual hint provided to the user when they hover the mouse over a user interface element. On most platforms this is in the form of a small yellow-ish window containing descriptive text.
Tooltips are available for some widgets starting in ASL 1.0.18.
Semantics / Rationale
Tooltips are not really a standalone entity; rather, they are an augmentation to preexisting widgets.
A tooltip for a widget is defined using the
alt tag in a layout. For example:
my_button(name: "Put them in the iron maiden", alt: "Execute them!");
The API is implementation-defined on a per-platform basis; in the case of Mac OS X and Windows XP, this can be reduced to a single API call that augments a control/window with tooltip metadata.