First off, best overall art app across iOS, replaces a lot of my workflow in photoshop as well.
I apologize if this is a repeat, but I would like to suggest adding a eyedropper option when the color editor is open. Using the eyedropper would not close the color editor, but any color selected would load into the color editor as the selected color in real time. Once you take your pen or finger off the screen you could adjust saturation and brightness with the color editor still open. There would need to be a brush button, to switch back to painting. It would be beneficial to add it too the gradient tool as well.
Second request would be for some dynamic guides tools. Arc, Elipse, Custom Line Guide creation tools. Similar to tools found in Infinite Painter. I have attached some photos in hopes to explain this.
Thank you for your continued work on this great app. I would suggest a paid update at some point, to further fund your work on this program as well. 2.0 maybe?