The Quick Chart gadget is a miniature version of the well-known thinkorswim Charts functionality. Despite its small size, it shares almost the entire functionality of Charts, including studies, drawings, charts style, and many more. It is especially useful when you work with another major thinkorswim component, but still need a chart for getting the full picture.
Note, however, that due to restricted dimensions of this gadget, some graphic elements that you are used to working with in the full-scale Charts might not be visible. In this case, consider using the Charts tab of the main window. Alternatively, you might want to detach the gadget and resize it according to your preferences (see the Left Sidebar article for details).