For those who prefer to use Google's email options, there does seem to be a clear difference between those who prefer Inbox by Gmail and Gmail. The former is the newer of the two and comes with some organization features included. However, Gmail being the long-term Google email resident does mean that it has built up quite the repertoire of features over the years. Ones which for those who have tried the move over to Inbox, find the email client a little too limiting in some respects.
However, Inbox is growing in terms of its features and does see a steady stream of updates coming through. Although, most of those updates bring with it features which are already available on Gmail. Much is the case with the latest feature that has now been added to the web version of Inbox. This is a feature which has already gone live for the web version, so it one which should be available to you right now.
From today, those using Inbox can make use of the ability to expand the compose window. Before the update, users simply had to make do with the standard pop-out compose window with no real ability to change the size of the window. Now, when you click compose, you will still see the same sized window appear at first. However, in the top right hand corner you will also see a new icon which when clicked effectively maximizes the window. This does not turn the pop-out into a full size window but does significantly increase the size of the window to a size which largely occupies most of the screen. Unfortunately, the size is not user adjustable in any way so you cannot further adjust the size of the compose window and instead do have to choose between either big or small. Although, this is still an improvement over the only choice of small that was available before. Not to mention, it is worth pointing out that Inbox remembers your choice. So once you click on the big window and compose an email, each time you hit compose the big window will be displayed again. You can see an example of the expansion in the image below.