We've made it easier to get to the new Composer. From the top of the Messages Overview page, click the "+ Message" button. You no longer have to click through to the old composers to get there. Alternatively, you can click the "Message" option in the shortcut button in the lower left-hand corner.
Now you can push to a set of tags in the New Composer. Rather than having to first create a segment, you can select them in the same message composer. Push to tags is still represented in our new Composer and API as a type of audience segment. You can choose an existing segment, or a tag segment you create on the fly: Note This is a change in behavior from the old Push and Rich Push composers, where you had to first create a segment in the Segments area of the UI.
In the New Composer, you can now save a draft of your work and come back to it later. Click the dark gray "Save as Draft" button in the upper right to save changes. After clicking, the button turns light gray to confirm your changes are saved. Note This is a change in behavior from the old Rich Push composer, which saved drafts automatically but did not provide feedback when it was saved.