Hm, for me the tooltip hides once I move the mouse away (as I would expect). In general Plasma does not discard tooltips automatically on click, because you might want to click on another button on this tooltip.

The problem rather seems to be that if Gwenview was not focused before hovering over the taskbar entry, after starting the slideshow (either via the context menu or via the tooltip), the panel will remain visible and only another click will bring Gwenview completely into the foreground. However, that's how it should work for "Click to Focus" in KWin's settings, shouldn't it?

Closing for now unless you have more detailed steps to reproduce, where the tooltip _never_ goes away.

I think that the tooltip should disappear immediatelly when gwenview goes to fullscreen mode. There is no reason to keep the tooltip visible while gwenview is in fullscreen mode.
I do not want to click another button from a tooltip while some app is in fullscreen mode. It does no sense.
If I want to click another button from a tooltip, I exit from fullscreen mode before.
Furthermore, the two other buttons from the tooltip (|< and >|) are also available in gwenview GUI running in fullscreen mode.
On my system palsma panel is not visible when gwenview goes to fullscreen, only the tooltip from gwenview entry remains on screen..

open dolphin
open a folder containing some pictures
use gwenview to open some picture
hover gwenview entry in plasma panel (tooltip appears)
click play button from the tooltip
Result: gwenview goes to fullscreen/slideshow mode
and plasma panel tooltip remains visible until I move cursor outside

Can we reopen this bug?

I wrote:
> Closing for now unless you have more detailed steps to reproduce,
> where the tooltip _never_ goes away.

You wrote:
> tooltip remains visible until I move cursor outside

Therefore:
> Can we reopen this bug?
Sorry, but no.

Besides, Plasma displays the tooltip and not Gwenview, and Plasma doesn't know anything about the difference between Gwenview or VLC, where the tooltip obviously should stay visible.

I will continue to use PhotoQt as image viewer.
Thanks.