Hi, second time for me to comment.
So why does the UI turned to grey when I interact? Did I press something or the game force to turn grey?
And I forgot to say this, when I select Helena skills, the UI looks like this.
Skill window will be fixed in next version. Thanks for reporting it.
As for the UI turning gray, I will need more information about that one. Screenshot would be perfect.
There are a few instances where UI turns gray that I know of and all of them are intentional. First instance are screens like building window or work window.
Second instance is the choice or number input window.
Reason for this is simple. I don't have the graphics finished yet.
The last instance is tied to the main quest progression. After finishing one of the dungeons, your UI changes depending on your choice made at the end.
Those are all intentional.
If you mean something else, then please provide a screenshot and I will look into it.