@wojtryb Much like you, I was a bit annoyed by using either the tiny color selector in the pop-up palette (right click) or having the advanced color selector docker take up a lot of screen space. This was one of the main reasons that lead me to create a plugin that offers a compromise between the two!
By default it lets you access the full “advanced color selector” by pressing an on-screen button, and then it automatically hides once you click the canvas (not as soon as the cursor leaves the color selector).
If this sounds interesting, you can find more info and a download link to my plugin here 
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(It’s all free and open-source)