As a feature suggestion I would like to extend the Gmail command pack to add attachments from Google Drive to an email, made in Gmail.
For example, you write an email and type /insert-xyz. This will search in your Google drive folder for xyz.pdf and inserts the first hit into your e-mail as an attachment.
One possible way to automate adding a GDrive attachment to Gmail is visualized below:
Currently this is not possible due to not changing window focus, see :Add GDrive document to Gmail