How to report bug with Preview copy+paste

Can anyone tell me how to submit bug reports and user feedback for the Preview app on Mac OSX High Sierra?

The bug report:

when I select and copy text in Preview, the text is not copied to the clipboard [PROBLEM!]

The user feedback:

• the highlight colours have been changed and are now too dark, making them distracting on the page and making it harder to read the highlighted text (because less contrast between black and dark colours)
• removing the highlight colours from the right-click context menu has made it a pain to highlight text.

I'm an academic. I was literally just about to write a post on my blog about how Preview fits so well into an academic workflow, and then I updated to High Sierra and... well, now I can't.