Dont know if this has been mentioned, but with the bookmark list (the up arrow on the right hand bottom) being on the extreme right hand side - what happens when we rotate the screen to portrait mode is that that bookmarks button become invisible and goes out of the screen in portrait mode.

On the MicroB the bookmarks button is on the left side, hence even in portrait mode you can access it.

From this perspective, often accessed buttons like bookmarks would be better being on left side, so that on rotated mode also, it will be within the screen real estate and visible.

Is this a doable suggestion ?