Hello. I have a bug with the taskbar not refreshing while hidden.

Steps to reproduce:
(1) Select a theme with a good amount of translucency (or transparency) on the taskbar
(2) Set the taskbar set to auto-hide
(3) Make the desktop background a slideshow, with fairly fast rate (so you don't get bored waiting for it to change)
(3) Make sure the taskbar is hidden when the background changes
(4) Mouse-over the taskbar screen-edge, to reveal the hidden task bar
(*)The task bar should now have a non-fully-updated translucency, resulting in weird appearance
(**) If something updates the task bar image (such as the kickoff menu, or taking a screenshot) then the taskbar updates to match the correct background

Here's an example of my taskbar when it looks like it should



Here's an example of my taskbar when the previous background was yellow, and the taskbar has not yet refreshed

What video driver are you using? I've never seen this myself as far as I can remember.

I'm using the catalyst drivers, provided by the aur. I was using Chakra, where I was just using catalyst. Now I'm using antergos using catalyst-test, and the exact same thing is happening.

I haven't seen this on radeon (but with FOSS drivers), nor with Intel. I'm fearing it may be some issue with the driver.

"kcmshell5 kwineffects", filter for "blur", click the config button, disable caching of interim results. still a problem?

I soon lost all transparency altogether, even on Guake which uses its own transparency. I switched to open source drivers, and all transparencies were still gone. So i uninstalled plasma-desktop and went back to KDE4. Everything is working like a charm, and for good measure I'm using open source drivers.

Had the same issue when using panel transparency, not always refreshing properly. I'm using integrated intel and plasma 5.3.