Is your feature request related to a problem? Please describe.
I cannot customize description label content offset. When I use EK as the DEBUG logger, sometimes the log info will be lengthy and the content offset is not good-look.

Here is the log info.
<img width="545" alt="Screen Shot 2019-08-23 at 6 36 20 PM" src="https://user-images.githubusercontent.com/12584632/63587370-6d5d1200-c5d6

What kind of feature would you like to see?

When end dragging RGB sliders on a real device, the targeted color value sometimes changed. Lifting off the finger seems to change the slider position.

How does it work in detail?

This could be solved by either doing some fancy zoom animation (depending on dragging speed) or by making right assumptions about the targeted color value.

Wha

We should set the popoverPresentationController's sourceView and sourceRect to prevent it form crashing on larger devices.