To use Widget["TextPanel"], you first need to load GUIKit using Needs["GUIKit`"].
Typically used to display HTML or RTF styled content.
There are three default text widgets provided within GUIKit: Widget["TextField"], Widget["TextArea"], and Widget["TextPanel"]. Widget["TextField"] is typically used for single line input using a single font, while Widget["TextArea"] would typically be used to display or take multiple line input also in a single font style. Widget["TextPanel"] is used less often, but has the benefit of displaying stylized text either as plain text, HTML 3.2 compliant text, or RTF styled text.
In its most basic form, Widget["TextPanel"] can display plain text just as Widget["TextArea"].
This widget would typically be useful to simplify laying out slightly more complicated text blocks using a single text string but including style information. You can also take advantage of the "path" property by specifying an external source for the text content, either as a relative local file or even URL-based paths. You can also support eventing off hyperlinks in any HTML you provide in the text, allowing for custom hyperlink actions or forwarding standard web URLs to a Mathematica front end to open in the user's chosen web browser.
EXAMPLES
Basic Examples 
