A CSS pseudo-class is a keyword added to selectors that specifies a special state of the element to be selected. For example :hover will apply a style when the user hovers over the element specified by the selector.
Clicking on this button will open a Symbol Dialog showing the font family selected if the font is already installed in the system. The Unicode of the selected character will be inserted on the page like "\f020". For example, if the font family selected is "Fontawesome, serif" and Fontawesome is installed on the Windows, clicking on this button will shown the following dialog. Assume that the first character on the top left corner is selected. The code "\f000" will be inserted to the "content" field.
