I updated to the latest snapshot yesterday and everything seems fine except the translucency on the panel and the folder widget. I remember in KDE4 that I could adjust translucency, but I do not see that option in Plasma 5. Any ideas?
No, you couldn’t change the translucency in KDE4. This was and still is determined by the used Plasma theme.
Does it help if you disable the “Blur” effect?
I had a very similar problem with the transparency, (using Air openSUSE).
The “Background contrast” effect seemed to be the culprit, unchecked translucency is completely lost, checked restores it to normal. (I’m sure that’s not quite how it’s meant to work…)
I seem to remember I could, but my memory may be faulty.
Anyway, I disabled the “blur” effect, and it had no effect. If I enable “Background contrast” it also has no effect, but if I then disable it, my panel becomes translucent for a couple of seconds, and then reverts back.
No, this was only possible in KDE3, which didn’t have real translucency at all. Kicker faked it by reading the screen content underneath and calculating a translucency effect in software.
This “feature” got removed in KDE4.
Although you can of course adjust it indirectly via the Plasma theme, for a custom value you could modify the theme, it just consists of standard SVG images.
Anyway, I disabled the “blur” effect, and it had no effect. If I enable “Background contrast” it also has no effect, but if I then disable it, my panel becomes translucent for a couple of seconds, and then reverts back.
Hm. Just to be sure: you do have Compositing enabled, and set to OpenGL? (Configure Desktop->Display and Monitor->Compositing)
I’m pretty sure Translucency doesn’t work without compositing, and I think it needs OpenGL too, not sure whether it works with XRender.
IIRC, there was a bug fix in 5.3.2 though that fixed a too big translucency under certain circumstances. Maybe that’s why you see less translucency now?
What theme are you actually using?
This is probably why I “remember” it. 
Hm. Just to be sure: you do have Compositing enabled, and set to OpenGL? (Configure Desktop->Display and Monitor->Compositing)
I’m pretty sure Translucency doesn’t work without compositing, and I think it needs OpenGL too, not sure whether it works with XRender.
I am using OpenGL with the EGL interface. I checked with the GLX interface and OpenGL 2.0 and 3.1. Under all conditins (i.e. all four iterations) the symptoms remain the same.
IIRC, there was a bug fix in 5.3.2 though that fixed a too big translucency under certain circumstances. Maybe that’s why you see less translucency now?
What theme are you actually using?
I am using Breeze Dark. Interestingly Air and Oxygen allow the panel to be translucent, but all the others do not. (I have only default themes)