If you round the corners, make sure that by moving the mouse into a corner of the screen, you grab the window. Otherwise I'll be cursing again and search for a way to disable that. Just like I did with the current version. (The preview of the selected theme shows round corners, but my windows have rectangular corners and I have no clue what I did back then).

The confusing thing about focus / hover colors is having to move away the mouse in order to see weather it's focused or toggled.

/me thinks that hover colors are more confusing than helpful, especially if they are similar / mixed with the "pressed" color. I have a mouse cursor to indicate the position of the mouse.

In T10891#204916, @ngraham wrote:

In T10891#204905, @michaldybczak wrote:

I updated to Plasma 5.17 last night and the first thing I noticed were... huge, ugly shadows. This was a surprise.

It's a surprise to me too because we didn't change the shadows at all in this release. :)

I do not like the shadow because the video in the next window will look broken,
but not having a shadow, I need window borders not in gray-on-gray. Currently the windows are not visually separated.