When hovering on stability percentages in the server browser, a tooltip
now shows the total downtime in the past 30 days, number of incidents,
their average length and the longest's duration.
Sometimes and randomly, a HListView/HGridView delegate's
add/populate transition will stop before completion.
This especially happens on startup when loading a large room list,
one room might get stuck and left tiny or invisible, despite its
normal space still being taken.
