My concern with this is that Plasma's tooltip appearance is currently very ugly: When you move between two bottom panel tooltips of different vertical size, as it resizes, the lower edge of the tooltip will "detach" from the panel. It looks like the tooltip "jumps" in a Flappy Bird-like manner. This looks so embarassingly shoddy and bad consider it unshippable to end users. I think until we fix this, we should avoid making tooltips different heights at all costs.