Introduces the concept of action tabsets - usage of TabSet and Tabs
in between the action buttons to allow richer set of capabilities that
can be offered to the user.
Goes along with c8d0cdec99c95dbed3b58ebcc098cc9d22c58206 that implements
a change to the CMS actions.
Put "File upload complete" and "back to folder" together. Turned 'File
upload' into a message, and updated the message styles.
Moved allowed file types into the area where users are uploading files.
This is a temporary fix until js tooltips are implemented, at which
point, these details will be shown when clicking a question mark beside
"Choose files".
Added small animation effect to files when opening iframe to edit. Now
slides down, rather than just appearing open
Linked to silverstripe/silverstripe-cms#223
* Add arrows back to edit-all toggle button
* Don't show dimensions if the item being inserted doesn't have them.
* Set pop-up windows to be a percentage of the window height for better
use of space
* Fix broken fieldholdersmall styling within files edit
* Add placeholder if no preview
*Take out minFileSize so upload will work on Android phones
Fixed the calculation of height for the upload (non AssetUploads) area
so that the save button would show. Took off the min-height, as this
will cause UI issues when there are multiple files open for editing.
