If you put two sliders side by side and enable the “hover shows current value”-feature, the value displays fine, then when I drag (so the value changes) and the mouse ends over the second slider, as soon as I release the mouse button, the bubble for the first slider disappears, but even though I’m now hovering the mouse over the second slider, no bubble appears for that one. Unless I move the mouse by 1 pixel.
The weird thing is that the new slider definitely gets its hover-message right away (before the mouse has to be moved). My custom look and feel draws a hovered slider slightly differently than an un-hovered one, so I can see it being highlighted, but the bubble doesn’t show.