On narrow windows, the items on the right side of the composer menu disappear and there is no indicator that they even exist until you make the window wide again. On mobile this means rotating the phone, which then (on my clunky samsung galaxy note 2) makes it impossible to edit because the keyboard and composer header takes up the whole screen.
The most important item on this menu for me is the options item, so I can get to the whisper function. Maybe an easy answer would be to move it left, say next to the upload item?
A more involved answer would be to provide an indicator that there are hidden items off to the right and some sort of horizontal scrolling or pulldown to reveal the hidden items. It could look like the options popup.
I do have the formatting toolbar plugin installed, which pushes the options item all the way to the right so it’s the first to get cut off on narrower windows. @Steven maybe you could contemplate having your formatting items display to the right of the options item? Or have your formatting items display in a popup like the options?
Screenshots - this post on meta with narrowish window, no options item:
new post on my site with formatting toolbar, much wider but still no options item: