Thanks for your interest, for the kind words and for your question.
[mla_gallery] supports the "ids" parameter, but the default behavior restricts display to those items attached to the post/page; that's what the WordPress
[gallery] shortcode does. You can code
post_parent=all to display anything in the Media Library, as explained in the documentation:
For WordPress 3.5 and later, the "ids" parameter lets you specify a list of Post IDs. The attachment(s) matching the "ids" values will be displayed in the order specified by the list.
You can use the "post_parent" to override the default behavior. If you set "post_parent" to a specific post ID, only the items attached to that post are displayed. If you set "post_parent" to "current", only the items attached to the current post are displayed. If you set "post_parent" to "all", the query will not have a post ID or post_parent parameter.
I am working on adding MLA support to the WordPress 3.5 "Add Media" popup dialog, responding to these topics:
Filter media when adding to post/page
Feature Request: Add Media Dialog: Search by Att. Category"
Thank you and question about possible future feature
Your suggestion to also support the "visual" edit mode is a good one, and I will consider it for a future release. It's one element of a user interface that would support all of the
[mla_gallery] parameters. That's a larger effort but a worthy goal.
Thanks your question, the suggestion, your patience and for using the plugin.