What it does
It wraps '<div>' elements around one or more blocks and gives the possibility to give these elements a CSS class. 

Why not setBlockWrapperStart?
This add-on is a replacement for 'setBlockWrapperStart' that some people define in their templates to wrap blocks. The problem with the setBlockWrapperStart is that all blocks get the same structure and it's not very easy to make an exception for one block without creating a new area.

Why not an HTML-block?
The HTML-block *could* do the same, but is a bit too simplistic. For example, it won't give a fixed height to the closing DIV in editing mode.
 

The Block Wrapper is simple and is handy if you have for example a sidebar with various block designs that need to be wrapped. This plugin also works with Stacks.

See also the documentation page.

Updates:

2014/10/08: 1.2.5.
Merge translations from Transifex.

2014/03/27: 1.2.1.
- Fix bug in open / close templates when editing a stack.

2014/03/20: 1.2. 
- Checked compatibility C563.
- Improved block dialog with ui styling.
- Make 'open' template default.
- Fix bug when block is added and no caption is shown.
- Code clean up.

2014/02/27: 1.0.1.
- Updated icon.
- Added link and attribute field.
- Changed open and close templates!