Up to now I have constrained an attachment image (picture) to 500 x 500 pixels.
Given the unused space to the right of most pictures on posts (as pictures are displayed vertically, not side by side), I have just updated the picture attachment size to 640 pixels wide x 480 pixels tall, a common landscape picture resizing option in most Photo Editing Programs.
This will mean wider pictures at no cost to thread length and easier for users to resize their landscape pictures before attaching to posts.
Note, this means that portrait style pictures are now limited to 480 pixels tall.
I have updated the FAQ on
Attaching Files to Posts.
