The topic window or the Tabbed Document pane displays the topic(s) that you are editing currently. Select File > Options > Allow Editing Of Multiple Topics to edit multiple topics concurrently. You can paste objects and selections across multiple topics. You can select horizontal or vertical tiling of topics.
The Design and HTML buttons in the topic window let you switch between Design Editor and HTML Editor.
When multiple topics are open, click the down arrow button in the upper-right corner of the Tabbed Document pane to display the list of open topics and navigate to any topic.
Take advantage of fixed buttons in the Tabbed document pane to open and close topics quickly.
Right-click a tab to find options to save the active topic, close the active topic, close all topics, close all but the active topic, and create horizontal or vertical tab groups.