It seem that it was intentionally implemented to let you compare a colour you picked or something, but in recent mypaint builds from the ppa,
when you pick a colour, the colour picker square showing the colour you picked would stay on the screen forever, until you hover over it with the cursor.
I find this behaviour extremely annoying/distracting. Its like one of those pop up ads that you need to manually close every time they open - it breaks the flow of work,as it makes you do one extra action every time you pick a colour. I dont need that box to stay there and I certainly dont like having to hover over it every time to close it. It tends to distract me a lot. It's not auseful enough to be worth the extra work.
Can we (optionally and even by default) disable this colour picker behavior??
If you want to keep it, then can you please tell me how to disable it completely? I will gladly open that python file and add some # //
Please

On a side note:
This made me notice that the shape of the color picker picked color preview being a square is more distracting than if it was a circle. Why is a square more of a sore thumb you ask?
Some drawing software has that in the shape of a circle. I think they do it because the circle has no pointy edges. Most drawings are made of curvy lines and very rarely are they made of completely horizontal and vertical lines. Mathematically correct square shapes that are not distorted by perspective!
This makes the pop up appear as an object that is hovering over the drawing- obstructing parts of it.
When you see that with your periferal vision, your mind immediately identifies it as a foreign element that is floating over a part of the canvas - something foreign.
When its a circle, that visually somehow makes it more acceptable for the periferal vision.
It's important to not have any distractions and be able to always keep your vision clean of things that pop over the canvas. Thats why I prefer to keep my dialogs in the right panel instead of floating over the canvas.
If its a bug, sorry for the rant. I hope its a bug