Added filtering for the Tab create.

You can now type strings to filter down the create pills.
You can also just use the mouse.
Currently it's not hooked up to actual creations.

Also removed the make_empty and is_empty methods from the Drawables interface.
This is because it exposes the underly implementation of how it makes things
visible or invisible.
Instead the Drawable now has show and hide methods.
The hide will immediately remove the data from the device.
The show will simple set a flag recording the fact that it is visible.
The unpack routine will need to be called to actually load the data to the device.