In the upper left corner, there is a button, that switches between the launcher and developer mode. I had no idea that this is actually a button. I thought it was decoration! I was like 'oh wtf you can click that?!?!?'
Then on the left there is also buttons to hide or show your workspaces. I did not know what they do. When you click them, they change color to indicate a status of either being activated or not activated. But the color difference is not high enough to distinguish between them atm. But even if you made the color more different, I couldn't tell wich color indicates wich state... E.g. if they were black or white, i still wouldn't know wich color indicates wich status. And then I'm like 'Wtf there is a bright button and a dark button, but I don't know if bright means activated or not activated' so yeah.
In the file list itself there seem to be arrows missing. (The triangles you click in file explorers to expand folders )
On the right I did not understand the plant button. Apperently it's for saving resources. Instead of this button it could just ask to be minimized into tray when klicking the close button?
I also did not understand the button with the circles. Looks like a share button.
Overall the buttons on the right seem to work weird. Pushing a button makes a frame pop up from the right side. Pushing multiple buttons makes the frames stack unto each other. I got a bit lost when I was playing around with the buttons and had multiple frames pop up. I tried to close some frames, but I forgot wich button closes wich frame and it made me feel like I am too stupid to use this Software... :(
Idk, maybe good old tabs work better for this kind of stuff?

I'd also like more clear borders for different window elements. E.g. in player mode there is no clear border for the list on the left, wich des not look clean to me.

>Yip. Icons are a horrendous task. There is so much that has to be accurate in aspects like sympolism, context, style and colors (ouch.) to achieve certain results, that its pretty hard to keep in good without years of experience. We hoped that adding tooltips to most functions gives the needed help. Still some work to do. On the other hand, understanding Icons is a learning process. For sure you won't get used to the tool as any other application that is limited to wide-spread basic icons but if you understand once their meaning your brain might acces their information faster.

Woooow don't overthink it too much. They are just buttons. :) I think it's a problem with many modern "applications" the try to look "clean" and "minimalistic" and "easy" but in the end they are totally horrible to use, because the designers seem to have thought too much about the looks and human interaction and in the end nothing fits together and when you want to get to some menu, you have to try and click around like a madman to find the stuff you were looking for.
I never had these problems with classic Software, but these new designs really drive me mad from time to time. :)

Edit: Windmill is not horrible to use, this is more a rant about modern software in general. D: