Better introduction to issue inline editing
As I mentioned in https://gitlab.com/gitlab-org/gitlab-ce/issues/37474#note_46680455, that issue's proposal doesn't properly solve the problem and possibly aggravates the current UX, where the edit button is clearly visible and aligned with other issue actions.
I think the placement of the button defines the scope of what you're editing better, which I believe is the main purpose of this change. I believe we shouldn't be discussing putting this feature on par with editing a comment (same placement and style) because the issue description is not a “big comment”, it's a different kind of content.
My concern right now is that proposed the visual treatment and using (only) an icon doesn't help highlight this frequently used feature, it looks more “buried”. Furthermore, with this visual weight, placing it below the “Close issue” and “New issue” buttons, which are colored, makes it lose a lot of its needed visual weight. Currently, it's placement before those colored buttons (Edit, Close issue, New issue) in a left to right reading direction, helps highlight it even though it lacks the color of its neighboring buttons.
Since we're trying to streamline inline editing, I would try to stick with the common design pattern. Example:
However, this might introduce other issues when the user tries to interact with elements in the description (checkboxes, images, links, heading anchors). These should still be interactive if the user clicks or hovers them.