You can create a link that displays an HTML topic in a pop-up rather than in the default browser or viewer. A pop-up supports HTML formatting, images, Dynamic HTML, link controls, and other HTML features of the destination topic. When a user clicks the link, the pop-up opens and sizes to fit either the content of the topic or dimensions that you specify.
A pop-up can be used only to link to a topic or bookmark within the project.
1)In the Design Editor, place the cursor where you want a link, or select text or an image to define a hotspot.
2)In the toolbar, click the Insert Popup button .
3)Select Hyperlink Options.
4)Select a size option. If you choose Custom-Sized Pop-up, enter values in points in the Height and Width boxes.note: Scrolling inside auto/custom pop-ups may not work in Multiscreen HTML5 output on some devices.
5)Under Select Destination (File Or URL), select a topic , bookmark , or frameset.
note: A link within a pop-up to another pop-up doesn't work in the HTML Help viewer or in Internet Explorer.