A Blender add-on that replaces the default Shape Keys panel with Shape Keys+, a plus-size panel containing extra features for creating, sorting, viewing, and driving shape keys. The Blender Artists thread can be found here.
The main feature of Shape Keys+ is the ability to create folders for easy sorting of shape keys. A shape key folder is a shape key in itself, though few things that work for normal shape keys will also work for folders.
Since a folder is a shape key, it must be created from the drop-down menu next to the Add Shape operator (plus icon) on the right-hand side of the panel. This will create an empty folder at the location specified by the Add/Copy setting of the Placement box at the top of the panel.
Shape keys and folders may be parented to and unparented from folders. This is done by selecting the large Specials drop-down menu on the right and highlighting Set Parent to.
To delete a folder without also deleting all its contents, click the X icon on the right. The standard Remove Shape operator (minus icon) will delete both the folder and its contents.
Without Shape Keys+, copying a shape key is a tedious task that requires you to manually hide all but one shape key and set all of its values to default in order to create an "image" of your model, then use the New Shape From Mix operator to turn that "image" into a new shape key.
With Shape Keys+, this is all done with one button. On the right-hand side of the panel, there is a button with an icon of a clipboard on it. This button is the standard Copy Shape operator, which works for regular shape keys and shape key folders, including the contents of said folder.
- Copies the raw shape key data, ignoring modifiers such as drivers, vertex group, visibility state, and current value
- Copies the name of the shape key and flips the ".L"/".R" suffix if Mirrored is selected from the drop-down menu
- Copies the range of the shape key value (min/max sliders)
- Copies the shape key value at the time of copying
- Copies the shape key's reference to its vertex group
- Copies the shape key's reference to its relative key (also known as "Basis" by default)
- Copies the shape key's interpolation value (a setting used when Relative mode is disabled)
- Copies the shape key's visibility state
- Does all of the above for folders and their contents as well
- Copies the shape key's driver
- Copies the shape key's animation data
When a driver exists for a shape key, its properties will appear at the bottom of the Shape Keys+ panel for easy access. This section of the panel contains almost all features of the Drivers tab from Blender's Graph Editor. It lacks features from the Modifiers tab, however.
In the Shape Keys+ driver editor, variables also have extra features. Here, they can be freely moved up and down, as well as to the top and bottom of the list. Like shape keys, driver variables can also be copied using the button with the clipboard icon.
The obscure expand/collapse icon at the bottom of the shape keys list is a button that toggles filtering options. In addition to the default Shape Keys panel's filtering options, Shape Keys+ includes an option to only show shape keys above or below a certain value, as well as an option to skip filtering of folder contents when the folder itself has a valid name.