WICKET-3370 prepared the terrain (all major browsers except IE already support it).
I will make a Git pull request for getting this into the master branch.
Here is what the changes do (commit comment):
Added the possibility to select multiple files in the OS dialog for
browsers that support HTML5 'multiple' attribute. For browsers that do
not support it, or if you do not set the boolean to true, it will behave
the same as before.
- easier select multiple files from multiple folders
- shows the multiple files after choosing them - one per line
- the delete buttons are aligned instead of positioning after the
variable length file names
- useless and confusing "C:\fakepath" in filenames reported by some
browsers (in multiple with single select mode) are now hidden.