When we use Drag and Drop feature in IE8, there's a pop-up window requesting the user to install Google Gears.
However, the pop up window leads to a dead end since Google Gears have been deprecated and HTML5 has taken place. So the user has no ability to install the Google Gears and the Drag and Drop feature doesn't work.

Steps to reproduce:

1. With Confluence 4.1.5 go to any page, Tools > Attachments and attempt to Drag and Drop any file.
2. You'll get a pop up requesting to install Google Gears.
3. You'll see that it will lead to a dead end.

Workaround:

You have to manually install Google Gears, in order to Drag and Drop feature to work. You can download from here.