Callback - getImage

Gets the image for this control.

If we set to an string value, we get the built-in icon for that .

link - gregmaxey.com/word_tip_pages/ribbon_images_labels_part_I.html 
link - gregmaxey.com/word_tip_pages/ribbon_images_labels_part_II.html 
link - gregmaxey.com/word_tip_pages/ribbon_images_labels_part_III.html 
link - gregmaxey.com/word_tip_pages/ribbon_images_labels_part_IV.html 
link - gregmaxey.com/word_tip_pages/ribbon_images_labels_part_V.html