Ensure that tooltips are only activated when the associated UI element is currently the hot item. This prevents tooltips from being activated for UI elements that are currently not enabled due to them being behind a popup or outside of a clipping rect.
When the activation rects for two tooltips overlap, this always causes the first tooltip to be rendered.
This is changed so the last active tooltip is rendered instead, to simplify the usage of the tooltip function.
Render tooltip text correctly with multiple lines when the maximum tooltip width is limited.
Add missing padding when rendering multi-line tooltip.
Update doxygen documentation.