Toolbar's button should have width equal 23 pixels and height equal 21 pixels.
Every button is associated with two images in gif
The first image is associated with not pressed button and should have name ended with "_n".
The second image is associated with pressed button and should have name ended with "_a".
There are two images for empty button in Editor/ed_styles
folder of downloaded zip
They are ed_empty_n.gif
Using these images and PhotoShop
we make two new images for our new button Insert Date
They will be ed_date_n.gif
These images should be placed to Editor/ed_styles